Public Health Consequences and Cost
of Climate Change Impacts on Indoor
Environments
Prepared for:
The Indoor Environments Division
Office of Radiation and Indoor Air
U.S. Environmental Protection Agency
Washington, D.C. 20460
January 2010
Prepared by:
David Mudarri, Ph.D.
The Cadmus Group, Inc.
Arlington, VA 22209
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Contents
FOREWORD 1
EXECUTIVE SUMMARY 3
Introduction 3
Chapter Summaries 3
Chapter 1: Indoor Environmental Quality and Its Role in Protecting Public Health 3
Chapter 2: Climate Change Impacts on the Outdoor Environment. 4
Chapter 3: Impacts Of Climate Change On Indoor Environmental Quality And Implications For The
Public Health 6
Chapter 4: Public Health Cost of Climate Change Resulting from Changes in Indoor Environments 8
Chapter 5: Summary and Conclusions 14
INTRODUCTION 19
Purpose 19
Organization of this Report 19
CHAPTER 1: INDOOR ENVIRONMENTAL QUALITY AND ITS ROLE IN PROTECTING
PUBLIC HEALTH 21
Chapter Overview 21
Indoor Temperature and Humidity 21
Indoor Pollution 22
CHAPTER 2: CLIMATE CHANGE IMPACTS ON THE OUTDOOR ENVIRONMENT 29
Chapter Overview 29
Summary Outline of the Impacts of Climate Change on the Outdoor Environment 29
Mean Temperature Will Rise 29
Humidity and Drought Conditions Will Change 29
Heat Waves Will Be More Frequent, More Intense, and Last Longer 30
Heavy Precipitation Events Will Increase in Intensity 30
Storms Will Likely Become More Intense 30
Sea Level Will Rise 31
Forest and Grass Fires Will Be More Frequent and More Widespread 31
Pathogenic and Allergenic Diseases May Increase with the Potential for Mass Outbreaks 32
Outdoor Air Quality Will Worsen 32
Infrastructure Will Be Damaged and Adaptation Made Difficult 32
CHAPTER 3: IMPACTS OF CLIMATE CHANGE ON INDOOR ENVIRONMENTAL QUALITY
AND IMPLICATIONS FOR PUBLIC HEALTH 33
Chapter Overview 33
Impacts of Climate Change on Indoor Temperature and Outdoor Air Ventilation 33
Overview 33
The Importance of Temperature Control for Good Indoor Environmental Quality 33
The Impact of Heat Waves on Indoor Environments 34
Recommended Public Health Responses to Heat Waves 35
Ability to Satisfy Increased Demand for Air Conditioning May Be Severely Constrained 36
The Shift from Heating to Air Conditioning Increases Greenhouse Gas Emissions 38
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Pressures for Reduced Ventilation to Reduce Energy Use are Likely 38
Indoor Chemistry Effects from Outdoor Ozone 41
Moisture-Related Impacts on Indoor Environments from Climate Change 45
Ecological Shifts, Disease Vectors, Pests, and Increased Occupant Vulnerability to Indoor
Environmental Conditions 46
Implications 48
CHAPTER 4: PUBLIC HEALTH COST OF CLIMATE CHANGE RESULTING FROM
CHANGES IN INDOOR ENVIRONMENTS 49
Overview 49
Purpose of a Quantitative Economic Assessment 49
Methodology 49
Time Frame 49
Discounting 49
Estimating Baseline Public Health Costs of Current Indoor Environmental Quality
Conditions 50
Considerations Related to Environmental Tobacco Smoke and Radon 50
Baseline Cost Categories 51
Baseline Public Health Costs from ETS Exposure 51
Baseline Rates of Mortality from ETS Exposure 51
Baseline Public Health Cost of Mortality from ETS Exposure 52
Baseline Public Health Cost of Morbidity from ETS Exposure 52
Baseline Public Health Costs of Heat Waves 53
Baseline Public Health Cost of Sick Building Syndrome, Heat Waves, Allergies and
Asthma, and Communicable Respiratory Illness 53
Sick Building Syndrome 54
Allergies and Asthma 54
Communicable Respiratory Illness 54
Public Health Cost Impact Categories 55
Consolidated Cost Impact Categories 55
Level of Impact 56
Estimates of Public Health Costs from Climate Change Impact on Indoor Environments 59
CHAPTER 5: SUMMARY AND CONCLUSIONS 69
Overview 69
Warmer Temperatures 69
Implications 69
Reduced Outdoor Air Ventilation 69
Implications 70
Elevated Ozone 70
Implications 70
Extreme Water Events 71
Implications 71
Ecological Shifts 72
Implications 72
Economic Costs 72
Implications 72
REFERENCES 73
IV
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Foreword
This paper accepts the conclusions of the world scientific community that the warming of the
Earth over the past several decades has been caused largely by anthropogenic greenhouse gas
emissions and that such emissions, if continued, will likely lead to a variety of climatic changes
throughout the world. This is the general conclusion of the Intergovernmental Panel on Climate
Change (IPCC) and the U.S. Climate Change Science Program (CCSP). The IPCC was
established by the United Nations Environment Programme (UNEP) and the World
Meteorological Organization (WMO) to present a clear scientific view on the current state of
climate change and its potential consequences, while the CCSP is an organization of 13 federal
agencies working to improve our understanding of the science of climate change and its potential
impacts. These organizations provide up-to-date scientific information and reports on various
aspects of climate change, along with major references to the general literature.1 The literature on
the impact of climate change has focused almost exclusively on the outdoor environment.
Girman et al. (2008), however, rightly point out that the impact of climate change on the indoor
environment could also be substantial, and they identify several areas of concern such as greater
use of air conditioning, increased risk of mold from flooding, increased exposure to ozone
indoors, increased pressures to reduce ventilation rates, increased risk from vector-borne diseases
and increased risk of pesticide exposure. They also suggest that government agencies and non-
profit organizations provide information and programs necessary to design, construct, maintain
and operate indoor environments that are capable of protecting occupants from climate change
impacts. This document expands and elaborates on the issues raised in that paper.
Note: This report presents the findings, recommendations and views of its author and not
necessarily those of the U.S. Environmental Protection Agency.
1 Reports from the IPCC are available at www.ipcc.ch/. The CCSP provides a series of synthesis
and assessment reports available at www.climatescience. gov/Library/sap/sap-summary.php.
(websites available as of 1/11/2010.)
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Executive Summary
Introduction
Buildings protect people from the elements and otherwise support human activity. Unless managed well,
however, environmental conditions inside buildings have the potential to make people sick, cause them
discomfort, or otherwise inhibit their ability to perform.
Degradation in indoor environments resulting from climate change involves impacts to the public health
not heretofore considered in the climate change literature. A closer look at the impacts of climate change
on indoor environments strongly suggests the need to plan for indoor environmental protections to
mitigate potentially large increases in public health risks.
This report presents a preliminary analysis of the changes in indoor environmental quality likely to result
from changes in climate and assesses the potential public health consequences of those changes. This
report also provides a preliminary analysis of the economic cost of these public health consequences. This
preliminary economic analysis is intended only to help policy makers decide how important indoor
environmental concerns might be when setting priorities for further research or further policy exploration.
Chapter Summaries
Chapter 1: Indoor Environmental Quality and Its Role in Protecting Public
Health
Chapter 1 provides a rudimentary framework for understanding the critical factors that determine the
indoor environmental quality of buildings in order to better understand how climate change will affect
indoor environments and what the associated public health consequences will likely be.
Key Points from Chapter 1
Indoor temperature and humidity are important to public health. Moderately high temperatures
and humidity in buildings (e.g., the high end of the thermal comfort zone) have been associated
with increased occupant discomfort, perceptions of poor indoor air quality (Bergland and Cain,
1989; Fang et alet al., 1998), unsolicited occupant complaints (Federspiel, 1998),; reduced
productivity(SeppanenSeppanen and Fisk, 2005),; and adverse respiratory health symptoms(
Mendell et alet al., 2002). .The ability of buildings to mitigate the heat and moisture impacts of
climate change indoorss, particularly for susceptible populations, is therefore a concern.
Much of a building's structure, its furnishings and equipment, and its occupants and their
activities produce pollution. In a well-functioning building, some of these pollutants will be
directly exhausted to the outdoors through exhaust ventilation, and some will be removed as
outdoor air is brought into the building and displaces the air inside. However, the air outside may
also contain pollutants, which will be brought inside in this process.
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Reducing emissions from indoor sources (source control) and providing adequate outdoor air
ventilation play complementary roles in protecting public health by controlling indoor
environmental exposures to indoor pollutants. The use of air-cleaning devices can augment
source control and ventilation strategies.
As outdoor ozone enters indoors, it reacts with compounds found on the surfaces of commonly
used building materials, furnishings, cleaning products and other surface treatments, air
fresheners, and other products. The result is the production of carcinogens and irritants such as
formaldehyde, acrolein, other aldehydes, acids, and ultrafine particles that are often more toxic
than the original constituent compounds (Weschler, 2000; Nazaroff and Weschler, 2004). The
impact of these byproducts on public health can potentially quite significant.
Biocontaminants found indoors include mold, dust mites, and allergens from cockroaches,
rodents, and other pests. Biocontaminants can trigger allergies, asthma attacks, and other
respiratory conditions. There are many sources of excess moisture that can lead to
biocontamination. They include high humidity and condensation; wet conditions from spills,
flooding, or poor drainage of rainwater; leaks in the building envelope or from water pipes; and
poor HVAC maintenance.
A rigorous and adequately funded building maintenance program is fundamental to sustaining
good indoor environmental quality and energy efficiency in buildings. Inadequate attention to and
funding of maintenance budgets, or poorly trained personnel, often lead to malfunctioning
equipment or lack of moisture control leading to inadequate ventilation, biocontamination, or the
unintentional introduction of pollutant sources. There is ample evidence of the association
between common maintenance shortfalls and reduced health and productivity in buildings
(Mendell, 2003; Wargocki et al., 2002b; Cole et al., 1994; Raw et al., 1993).
Chapter 2: Climate Change Impacts on the Outdoor Environment
Chapter 2 discusses the impact that climate change is expected to have on the outdoor environment,
focusing on those aspects most likely to have significant impact indoors. The chapter covers gradual and
episodic impacts. For example, a gradual rise in mean temperature or precipitation will be accompanied
by episodic extreme weather events such as heat waves, storms, and heavy precipitation, which are
expected to be more intense and occur more frequently.
Key Points from Chapter 2
A recent U.S. Government report (USGCRP, 2009) provides a useful summary of anticipated
impacts of climate change.The main findings of this report are summarized below.
Warming over this century is projected to be considerably greater than over the last century. The
average temperature of the Earth has risen about 1.5 °F since 1900. By 2100, it is projected to rise
another 2 to 11.5 °F. By the end of this century, the average temperature in the United States is
projected to increase about 7 to 11 °F under high emissions scenarios and about 4 to 6.5 °F under
low-emissions scenarios.
Atmospheric conditions in northern regions will change from very cold and dry to warmer and
more humid. Droughts are likely to become more frequent and severe, particularly in the
Southwest.
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Excess heat events that now occur once every 20 years are projected to occur about every other
year in much of the country by the end of this century, and these very hot days are projected to be
about 10 °F hotter than they are today. The number of heat wave days in Los Angeles is projected
to double, and the number in Chicago is projected to quadruple if greenhouse gas emissions are
not reduced.
Heavy downpours that are now l-in-20-year occurrences are projected to occur about every 4 -
15 years by the end of this century, depending on location. The intensity of heavy downpours is
expected to increase. The l-in-20-year heavy downpour is expected to be between 10 percent and
25 percent heavier by the end of the century than it is now.
The destructive energy of Atlantic hurricanes has increased in recent decades. The intensity of
these storms is likely to increase in this century.
Cold-season storm tracks will continue to shift northward, and the strongest storms are likely to
become stronger and more frequent, with greater wind speeds and more extreme wave heights in
northern areas (e.g., Northeast and upper Midwest). Lake-effect snowstorms in the Great Lakes
region are likely to increase, causing potentially heavy snow storms such as the February 2007
storm in western New York.2
Assuming historical geological forces continue, a 2-foot rise in global sea level (within the range
of recent estimates) by the end of this century would result in a relative sea-level rise of 2.3 feet at
New York City, 2.9 feet at Hampton Roads, Va., 3.5 feet at Galveston, Texas, and 1 foot at Neah
Bay in Washington State. Sea-level rise will increase risks of erosion, storm surge damage, and
flooding for coastal communities, especially in the Southeast and parts of Alaska.
The western United States and Alaska will experience increased frequency of large fires and an
extended fire season. Deserts and dry lands in the arid Southwest and elsewhere will become
hotter and drier, and they will expand to the north and east and move into higher elevations.
Increased drought conditions will continue to encourage non-native grasses to invade the
Southwest, where they will provide fuel for fires, which are expected to increase in frequency and
intensity.
Unforeseen ecological changes could result in massive dislocations of species or in pest
outbreaks. With global trade and travel, disease flare-ups brought about by climate change in any
part of the world, particularly in poorer nations, have the potential to reach the United States,
where extreme weather events could undermine the public health infrastructure and make people
more vulnerable as disease transmission from food, water, and insects is likely to increase. Rising
temperatures and carbon dioxide concentrations increase pollen production and prolong the
pollen season in a number of plants that have highly allergenic pollen, presenting a health risk.
Emissions of volatile organic compounds (VOCs) and the formation of ozone outdoors are
expected to increase, as is the frequency and duration of stagnant air masses. Under constant
pollutant emissions, by the middle of this century, Red Ozone Alert Days in the 50 largest cities
in the eastern United States are projected to increase by 68 percent due to warming alone.
2However, the heavy precipitation is projected to eventually fall as rain rather than snow with increased warming in
the long term.
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The projected rapid rate and large degree of climate change over this century will challenge the
ability of society and natural systems to adapt. Adaptation will be particularly challenging
because society will not be responding to a new steady state, but rather to a rapidly moving target.
Climate will be changing continually and rapidly at a rate outside the range to which society has
adapted in the past.
Chapter 3: Impacts Of Climate Change On Indoor Environmental Quality
And Implications For The Public Health
Chapter 3 discusses how changes in the outdoor environment brought about by climate change will affect
the indoor environment and lead to changes in the health, comfort, and productivity of people as they
occupy their residences, schools, commercial and institutional buildings.
Key Points from Chapter 3
Temperature
Higher temperatures from climate change will increase the use of air conditioning, leading to
substantial increases in demand for electricity and the need for increased electricity generation.
However, areas that have little current air-conditioning capacityalong with substantial
disruptions in power generation and distribution created by other climate change impactswill
create unmet needs for cooling, resulting in increased indoor air temperatures.
Moderately high temperatures will likely result in perceptions of indoor air quality as being
poorer, with higher rates of unsolicited occupant complaints, sick building syndrome and lost
productivity, and potentially increased respiratory symptoms.
The increased frequency and intensity of extreme heat events will create stresses on indoor
environments that will not be fully met, causing increased morbidity and mortality from extreme
heat indoors.
Ventilation
Increased electricity demand and interruptions in supply are expected to raise energy prices,
which, combined with the desire to reduce greenhouse gas emissions, will likely encourage
individuals and public policy toward greater energy conservation through reduced outdoor air
ventilation in buildings.
Reduced outdoor air ventilation raises indoor concentrations of indoor-generated pollutants and
increases the adverse health, comfort, and productivity impacts of these contaminants.
Strategies are needed to protect indoor environments while reducing energy use. Such strategies
could include increasing the energy efficiency of equipment, employing ventilation strategies that
use less energy (e.g., separating outdoor air delivery from the heating and cooling airflow
requirements, or employing more natural ventilation), adopting ventilation strategies that are
more efficient in removing contaminants (e.g. displacement ventilation, increased exhaust
ventilation), and strategically integrating more air cleaning into the ventilation system. In
addition, a major effort to reduce pollutant emissions from products and materials used in
buildings would help reduce the need for ventilation to maintain adequate indoor air quality and
protect the public health.
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Indoor Chemistry
Climate change has the potential to produce significant increases in near-surface ozone
concentrations throughout the United States (EPA, 2009). Ozone is known to react with many
VOCs found indoors to create a variety of chemical byproducts with potentially troubling adverse
health consequences that could present a significant unanticipated public health issue. Recent
studies indicate that ozone reacts with the constituents of carpets, cleaning products and air
fresheners, paints (particularly low-VOC paints which use linseed oil), building materials, and a
variety of surfaces to produce some irritating and toxic compounds such as formaldehyde and
other aldehydes, acid aerosols, and fine and ultrafine particles (Weschler (1992, 2000, 2004,
2006, 2007); Weschler and Shields (1997, 2004); Nazaroff and Weschler (2004); Morrison (
2008,); Levin (2008)).
Of particular concern for ozone reactions is the prolific use of cleaning products and air
fresheners, which contain selected terpenes (e.g., a-pinene, limonene, and isopropene) that readily
react with ozone. Studies suggest that such reactions produce substantial quantities of toxic
secondary byproducts. In addition, unstable byproducts such as the OH radical can set off a
cascade of chemical reactions that, depending on the indoor and outdoor air constituents, can
produce further stable and unstable byproducts. The potential impact of these reactions on the
public health is just beginning to be appreciated.
Improved testing to reduce pollutant emissions from products and materials and to reduce the use
of chemical compounds in products that readily react with ozone would be important public
health strategies to consider.
Moisture
Increased relative humidity from climate change will increase the moisture content of materials
indoors and thus increase the risk for mold growth. These conditions will be exacerbated by
heavy periodic rainfalls that will likely stress the ability of buildings of all types to adequately
manage excess water flow.
The current prevalence of dampness and mold conditions in U.S. buildings already suggests a
lack of proper building defenses against excess moisture flows. In the absence of increased
maintenance and retrofit activity in the U.S to control moisture, these problems could easily grow
exponentially in the face of increased humidity, heavy rainfall, storms, and flooding. The rampant
mold problems caused by flooding during Hurricane Katrina (Hamilton, 2005) provide ample
evidence that mold issues could be a significant problem related to climate change.
Damage caused by flooding plus the abundance of water available to pests will likely increase
pest-harborage opportunities and increase the capacity of buildings to support pests infestation.
(Cockroaches, for example, are primarily attracted to water sources and food debris.) An increase
in pests could increase exposure to pest allergens, infectious agents, and to pesticides.
A careful analysis of regional vulnerabilities to moisture intrusion into existing buildings, and to
building practices to prevent such intrusions in new building construction, would be worthwhile.
In addition, widespread dissemination of guidelines for remediating dampness and mold in
buildings, integrated pest management techniques, and revised specifications for temporary
housing could help mitigate moisture-related public health consequences of climate change in
buildings.
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Vulnerability to Diseases, Pests and Pesticides
Changes in the ecological balance brought about by climate change can alter the geographical
distribution and biological cycle of many disease vectors, allowing the establishment of new
breeding sites and bursts of disease carriers, thus posing significant disease risks to humans. In
addition, climate change is expected to deplete the upper stratospheric ozone layer and thereby
increase population exposure to ultraviolet (UV) radiation, which could suppress immune
responses to various diseases and to vaccinations (de Gruijl et al., 2003) and could leave the
general population more vulnerable to disease outbreaks.
Increases in populations of structural pests, crop pests, and forest pests are also likely to increase
the use of pesticides and pesticide exposure both indoors and outdoors. Policies to encourage the
use of Integrated Pest Management (IPM) to minimize the use of pesticides would be wise.
Implications
In general, buildings will be used as shelters to avoid exposure to disease vectors outdoors, to
avoid excessive exposure to UV radiation, and to avoid extreme environmental events such as
heat waves. If indoor environments are to be relied upon to protect the public, a paramount
concern is whether the indoor environment itself will be sufficiently capable of providing
environmental conditions conducive to supporting the health and well-being of populations.
Attention to healthy conditions indoors becomes more important as populations become more
vulnerable by disease, UV radiation, and other environmental stressors. A hard look at building
design and maintenance practices in light of this vulnerability would be worthwhile.
Chapter 4: Public Health Cost of Climate Change Resulting from Changes in
Indoor En vironments
Chapter 4 provides a very rough estimate of the economic value of the public health impacts of climate
change on indoor environments described in Chapter 3. The estimates are limited to the economic value
of the impacts on public health and do not account for expenditures or for other adaptations that may
occur as society attempts to adjust to such impacts.
Key Points from Chapter 4
Methodology
The economic value of changes in public health, comfort and productivity are estimated in terms
of percentage increments to baseline public health costs associated with current inadequacies of
indoor environmental quality. The assessments are made first by establishing baseline public
health costs and then by estimating a likely percentage change from that baseline due to specific
climate change effects on the indoor environment. The total public health cost estimate is derived
by summing the public health cost of specific climate change effects.
The 75-year time frame adopted for this assessment is generally consistent with the time frames
used in most government publications concerning climate change. Since public health costs are
evaluated over time, discounting the value of future costs is appropriate.
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There are three time frame issues incorporated into the discounting procedure. The first relates to
situations in which a given health impact from exposure is delayed after an initial climate change
effect occurs. This is applied to premature deaths caused by long-term exposure to environmental
tobacco smoke (ETS). It is assumed that the full impact on premature death would gradually
evolve in equal increments over 70 years. The second relates to situations where exposure in the
absence of climate change is expected to change overtime. Since the prevalence of smoking is
declining, it is assumed that exposure to environmental tobacco smoke in the absence of climate
change would gradually decline to 40 percent of its current level over a 25-year period. The third
relates to the fact that climate change itself does not happen all at once, but is expected to evolve.
It is assumed that predicted changes would occur in equal increments over 75 years.
With the exception of the effect of heat waves, where the literature provides a basis for an impact
estimate, one of three levels of impact are chosen through reasoned judgment for each effect: low
impact (1 percent - 20 percent), medium impact (21 percent - 35 percent), and high impact (36
percent - 50 percent).
Pubic Health Cost Estimates
Tables ES-1 summarizes estimates of baseline public health costs from current indoor
environmental conditions. Table ES-2 provides consolidated impact categories used to
estimate public health costs from climate change impacts on indoor environments. Table ES-
3 maps the effect of outdoor climate change on indoor environments and identifies the
impact categories affected.
Table ES-4 provides the undiscounted estimates of the public health cost from the climate
change impact on indoor environments. The approximate range of total costs is $75 billion -
$175 billion per year. This represents in current dollars the annual cost burden that would
occur after 75 years.
Table ES-5 presents the discounting factors used to account for discounting and adjustments
described above using social discount rates of 3 percent and 7percent. Table ES-6 presents
the discounted and adjusted annual costs. The approximate range of total costs is $10 billion
- $60 billion per year. This represents the present value of the future varying annual cost
stream converted to a constant annual equivalent.
Given the uncertainties and the unrefined nature of these estimates, it is perhaps more
appropriate to conclude that the discounted and adjusted public health costs are in the low-to-
mid tens of billions of dollars per year, but could be in the high tens of billion of dollars per
year if all health impacts were included.
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Table ES-1: Baseline Economic Cost of Health, Comfort, and Productivity Impacts
Health or Exposure
Category
Approximate
Annual Cost
(Billions)
Comment
ETS exposure mortality
$369 (current)
$148* (future)
49,830 premature deaths from cancer, heart disease,
and SIDS (from CARB, 2005)
ETS exposure morbidity
$4 (current)
$2* (future)
Includes 24,500 cases of low birth weight and 17,000
new cases of asthma only (CARB, 2005)
Heat waves
$5
688 premature heat-related deaths including
hypothermia as a contributing factor (CDC, 2006)
SBS
$93
Midpoint of productivity loss of $73 billion from SBS
(Fisk, 2000) and $87 billion (EPA, 1989), adjusted for
inflation to 2008 dollars
Allergies and asthma
$6
Midpoint of $2 billion - $8 billion (Fisk, 2000),
adjusted for inflation to 2008 dollars
Communicable respiratory
illnesses
$13
Midpoint of $6 billion - $14 billion (Fisk, 2000),
adjusted for inflation to 2008 dollars
Total Baseline Annual
Cost
$490 billion (current)
$267 billion (future)
* Adjusted to 40% of the dollar value for declining smoking prevalence.
Table ES-2: Consolidated Cost Impact Categories
Category
Source
(1) Sick building syndrome (SBS)
Increased indoor temperatures and pollution from
VOCs, pesticides, and formaldehyde
(2) Heat waves
Extreme heat events
(3) Allergies, asthma, and respiratory symptoms
Moisture-related contaminants such as mold, dust
mites, cockroaches, and rodents, plus symptoms from
fine particles resulting from indoor air chemistry
involving ozone
(4) Communicable diseases
Ecological shifts that increase disease vectors and
from reduced immunity due to ultraviolet radiation
(5) All health effects except heat waves
Reduced ventilation, which increases all indoor air
contaminants. Includes all the effects in Table 4-2
except heat waves
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Table ES-3: Effects of Climate Change (Global Warming) on Indoor Air Quality
Climatological Effect
and Adaptations
Indoor Environmental Effect
Effect on indoor
climate and indoor
pollution
Effect on health,
comfort &
productivity
Value (cost) of health,
comfort, & productivity
change*
Outdoor Temperature
Mean rise in outdoor
temperature rise
Indoor temperature
rises.
Sick Building
Syndrome (SBS)
increases from
temperature rise.
Percentage increase in
SBS (1)
Increased use of air
conditioning
Potential for increased
off-gassing of VOCs.
Potential increase in
respiratory
symptoms
Percentage increase in
SBS (1)
Increased frequency and
intensity of heat waves
Inability of air
conditioning to
condition indoor air
Extreme heat stress
Multiple effects
Percentage increase in
respiratory symptoms (2)
Percentage increase in
premature death (2)
Outdoor Pollution
Increased outdoor
pollution (especially
particulates and ozone)
Increased particulates
and ozone come indoors
Increased ozone reaction
byproducts (indoor
chemistry)
Increased
respiratory ailments
Increased SBS and
respiratory
symptoms
Percentage increase in
respiratory symptoms (3).
Percentage increase in
SBS (1)
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Climatological Effect
and Adaptations
Indoor Environmental Effect
Effect on indoor
climate and indoor
pollution
Effect on health,
comfort &
productivity
Value (cost) of health,
comfort, & productivity
change*
Moisture and Water
Events
Increased mean outdoor
humidity
Temporary housing
provided in flooded
areas
Increased indoor relative
humidity, condensation,
and mold growth
Increased frequency and
intensity of extreme
precipitation episodes,
with flooding in inland
areas
Higher intensity of
storm surges and sea
level rise in coastal
areas, with increased
flooding in East and
Gulf Coast Regions
Increased harborage of
rodents
Increased wet, damp
conditions, building
damage, and mold
Increased rodent
infestation indoors due
to rodent migration from
outdoors to indoors and
possible cockroach
infestation due to
dampness
Increased use and
exposure to pesticides
Increased formaldehyde
and VOC exposures
Asthma, allergies,
and respiratory
symptoms
Asthma, allergies,
and respiratory
symptoms.
Allergies, asthma,
and respiratory
symptoms.
SBS from
pesticides,
formaldehyde, and
VOC
Percentage increase in
allergies, asthma, and
respiratory symptoms (3)
Percentage increase in
allergies, asthma, and
respiratory symptoms (3)
Percentage increase in
allergies, asthma, and
respiratory symptoms (3)
Percentage increase in
SBS (1)
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Climatological Effect
and Adaptations
Indoor Environmental Effect
Effect on indoor
climate and indoor
pollution
Effect on health,
comfort &
productivity
Value (cost) of health,
comfort, & productivity
change*
Outdoor Air Ventilation
Pressure to reduce
energy use to lower
GHG; because of the
cost of increased air
conditioning results in
reduced outdoor air
ventilation
All existing indoor
pollutants rise in inverse
proportion to reduced
ventilation
Increases in all
existing indoor air
health, comfort, and
productivity effects
Percentage increases in
all categories except heat
waves (5)
Ecological Shifts and
UV Radiation
Changes in population
and geographical
distribution of disease
pathogens, vectors, and
hosts
Increases in disease
outbreaks
Disease
transmission in
indoor environments
Percentage increase in
communicable diseases
(4)
*The numbers in parentheses correspond to the corresponding cost impact category in Table ES-2
Table ES-4: Undiscounted Public Health Cost Estimates
Category
Annual Public Health Cost (billionS)
Low
High
Sick Building Syndrome
1
19
Heat Wave Mortality
3
4
Allergy, Asthma, and Respiratory
1
2
Communicable Disease
3
5
Ventilation ETS (mortality)
40
80
Ventilation (morbidity)
1
1
Ventilation (other)
30
60
Total
79
171
Approximate Range
75 - 175
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Table ES-5: Discount Factors for Annual Equivalent Impact Estimates
3%
7%
Annual
Equivalent
Annual
Equivalent
Delayed premature death (70 yrs)
0.425
0.216
Incremental climate change (75 yrs)
0.405
0.202
Smoking prevalence reduction from 25 percent to 10
percent in 25 yrs
0.568
0.701
All effects combined
0.115
0.038
Table ES-6: Discounted and Adjusted Annual Equivalent Public Health Cost of Climate
Change on Indoor Environmental Quality (Sbillion)
3%
7%
Low
High
Low
High
Sick Building Syndrome
0
8
0
4
Heat Wave mortality
1
2
1
1
Allergies, asthma, respiratory disease
1
1
0
0
Communicable respiratory disease
1
2
1
1
Ventilation ETS mortality
11
23
4
8
Ventilation ETS morbidity
0
0
0
0
Ventilation other*
12
24
6
12
Total
27
60
12
26
Approximate Range
10-60
*Excludes heat waves
Chapter 5: Summary and Conclusions
Chapter 5 summarizes the impacts and discusses the implications for public and private actions to protect
the public health through improved indoor environmental planning and control. All of Chapter 5 is
presented below.
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Warmer Temperatures
Warmer outdoor temperatures caused by climate change are expected to increase indoor
temperatures.
While partly mitigated by increased use of air conditioning, overall, the rise in indoor
temperatures can be expected to have some health impact, including perceptions of poorer indoor
air quality, increased SBS symptoms, and some increase in respiratory symptoms. Greater use of
air conditioning will likely increase carbon emissions, which in turn will accelerate the warming
effect.
Temperature extremes are expected to experience proportionally higher increases than mean
temperatures, and extreme temperature events will occur more often. This will greatly increase
peak electricity demand, perhaps beyond the capacity to meet the increased demand for air
conditioning, and this will exacerbate the health effects from indoor exposure.
Heat waves will result in a host of health effects, including increased deaths of vulnerable
populations from indoor heat exposures.
Implications
Significant unmet needs for cooling through air conditioning will require greater attention to
alternative cooling strategies in building design (e.g., building orientation, roofing and window
systems) and operational practices (e.g., night cooling). This is consistent with the "green
building" movement, which may be further encouraged in response to climate change.
The generally agreed upon recommended public health response to heat waves is a notification
and response program. This approach does not address the likelihood that many buildings,
including many that are relied upon in these programs to be available to cool sensitive
populations, may not be capable of doing so due to disruptions in energy supplies and building
damages from other climate change events. Further consideration of this issue is needed.
Reduced Outdoor Air Ventilation
Non-industrial buildings account for almost 40 percent of the energy consumed in the United
States. The rise in energy demand for air conditioning combined with the need to reduce carbon
emissions is expected to result in reduced outdoor air ventilation of buildings. Since ventilation is
a primary means of controlling concentrations of pollution generated indoors, this is expected to
have a profound affect on all categories of health impacts associated with exposure to indoor
pollution.
Outdoor air ventilation was significantly reduced during the energy crisis of the 1970's.
Complaints of building sickness brought about the recognition that indoor air pollution can be a
major public health threat and that adequate ventilation is important for acceptable indoor air
quality.
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Implications
A major effort to install more energy-efficient ventilation equipment and more effective and
efficient ventilation strategies may be needed. These changes would reduce the energy used for
ventilation and mitigate the need to save energy by reducing ventilation rates. Such strategies
could include more reliance on natural ventilation or greater ventilation efficiency (e.g.,
displacement ventilation).
Efforts to increase control of indoor pollution sources and promote the use of advanced filtration
and air-cleaning technologies could allow ventilation rates to be modestly reduced without
affecting indoor air quality.
Elevated Ozone
Elevated levels of outdoor ozone due to climate change are expected to increase ozone levels
indoors where people spend most of their time, and where the public is traditionally advised to go
when outdoor ozone levels are high.
Ozone indoors is known to react with a host of commonly used chemicals and produce toxic
byproducts to which people indoors are exposed. The byproducts include fine and ultrafine
particles, formaldehyde and other aldehydes, acrolein, and other chemicals. Other byproducts are
unstable compounds that stimulate additional chemical reactions.
While elevated ozone is rapidly emerging as an important indoor air concern, the specific health
impacts from the reactive byproduccts generated by ozone are not well understood. Nevertheless,
it is thought that the often-cited health impacts from ozone and particulate pollution outdoors may
in fact reflect exposures to toxic compounds indoors from ozone reaction byproducts.
With ozone levels expected to increase, this issue may be one of the most important indoor
environmental impacts on public health due to climate change. Important chemicals of concern
indoors because they react readily with ozone include terpenes, which are natural oils
increasingly used in fragranced products and cleansers (including many "green" cleaning
products). The rapid growth of fragranced products and air fresheners may be of particular
concern in view of climate change. This issue is worth further study.
Implications
Fortunately, it may be possible to mitigate the potentially significant public health impacts from
direct exposure to ozone and from exposure to byproducts of chemical reactions with ozone
indoors.
Strategies to reduce direct exposure to ozone indoors could include the use of air cleaning
systems to remove ozone from outdoor ventilation air and from indoor air. Charcoal and other
chemical sorbents are used to remove ozone within filtration systems and are suggested for use in
high ozone areas. That these systems require careful monitoring and diligent maintenance
emphasizes the need for improvements in building maintenance. Further research into improved
gas phase air-cleaning systems may prove to be highly beneficial.
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The most direct strategy to reduce exposure to ozone-reaction byproducts is to have
manufacturers change their product formulations to reduce the use of those VOCs that readily
react with ozone. Filters typically found in HVAC systems may also be a cause of concern when
ozone levels are elevated. Filters continually collect dust particles that contain VOCs that may
react with ozone and create undesirable byproducts such as formaldehyde that is then delivered
into occupied spaces. In fact, formaldehyde has been shown to be a common product of reactive
chemistry on filters (Hyttinen et al., 2006). The synthetic media of the filters themselves also
appear to be a problem (Buchanan et al., 2008). This suggests the possibility that proper filter
medium selection or treatments could reduce adverse health symptoms from chemical reactions
with ozone.
Extreme Water Events
Extreme water events from heavy rainfall, flooding of interior rivers and streams, and flooding in
coastal areas caused by sea level rise are expected to put great strains on the building stock,
increasing infestations of molds, rodent, cockroach and dust mites.
Allergy, asthma, and respiratory effects from these problems are expected to increase
substantially. Problems are likely to be made worse by power outages and infrastructure damage
caused by extreme weather.
Providing temporary housing for displaced populations is expected to increase in areas
susceptible to flooding. Exposure to formaldehyde in temporary housing has been a problem and
will likely become a far greater problem unless provisions are made for removing formaldehyde-
laden materials from these units. Problems caused by inadequate ventilation and poor drainage
have also been experienced in some of these structures.
Implications
Delays in the ability to pump out water and dry buildings will likely extend exposures well
beyond the events themselves, and these exposures may become endemic if the time needed for
recovery extends beyond the time between extreme water events.
Areas where buildings are perpetually wet or very damp from extreme water events may become
uninhabitable and abandoned, leaving large swaths of economically depressed areas and causing
significant population relocation.
Research to identify vulnerable areas could provide advanced warning and time for the
development of mitigation strategies. Codes, standards, and the widespread dissemination of
guidelines to protect buildings from damage where possible, and to mitigate dampness and mold
problems, may be useful.
Ecological Shifts
Ecological shifts are expected to alter the breeding cycles and geographic distribution of many
disease vectors, and this trend raises the potential for major disease outbreaks in the United
States. The globalization of commerce and increased international travel adds to this threat. The
increase in UV radiation from climate change also has the potential to compromise a person's
immune system, making the population more vulnerable to disease.
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Implications
Reduced ventilation in buildings could expand the potential for disease transmission.
Building O&M practices could be critical elements of control, particularly in hospitals, medical
centers, schools, and other high-occupant-density buildings.
Cultural attitudes in the building community that consider maintenance to be an expense to be
minimized rather than an investment to be made in building environmental quality may need to
be addressed through educational and training programs. A change in attitude and a move toward
more scientifically based maintenance and cleaning practices would be needed.
Building policies and guidelines specifically addressing disease transmission may need to be
developed, widely disseminated, and promoted.
The improved design and construction of temporary housing would help protect the health of
displaced occupants housed in these facilities.
Economic Costs
The undiscounted public health costs of climate change impacts on indoor environments appear
to between the high tens of billions and two hundred billion dollars per year. These are annual
costs that would occur toward the end of this century valued in current dollars. Using social
discount rates of 3 percent and 7 percent, the discounted public health costs appear to be in the
low-to-mid tens of billions of dollars per year, and would likely be in the high tens of billions of
dollars per year if the full range of health effects were included in the estimate. These ranges
represent the current value of discounted annual costs that are expected to occur indefinitely into
the future.
Implications
From a public policy standpoint, the impact of climate change on indoor environments and public
health appear to be at levels that would warrant more attention. Focused study is needed to
determine how best to ensure that policies, building practices, and technologies are implemented
to prevent the degradation of indoor environments and ensure that buildings can fulfill their
primary role of providing indoor spaces that are supportive of occupant health, comfort, and
productivity in the face of climate change.
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Introduction
Implicit in many of the recommended societal responses to climate change is the assumption that
buildings will shelter the population from climate change impacts. But what kind of environments will
buildings offer under climate change conditions? Buildings exist to protect people from the elements and
to otherwise support human activity. However, unless buildings are managed well, indoor environmental
conditions have the potential to make people sick, cause them discomfort, or otherwise inhibit their ability
to perform.
Degradations in indoor environments resulting from climate change involve impacts to public health not
heretofore considered in the climate change literature. A closer look at the impacts of climate change on
indoor environments strongly suggests the need to plan for indoor environmental protections to mitigate
potentially large increases in public health risks.
In the United States, people spend the majority of their time indoors at home, work, school, or other
venues. Contaminants and climatic stressors found indoors are largely determined by how well buildings
shelter occupants from adverse outdoor conditions, what indoor conditions are created by the building and
its environmental control systems, and occupant activities. The public health risks from current indoor
environmental conditions are already quite large.3
Preliminary analysis suggests that climate change can seriously affect indoor environmental quality
through several mechanisms that have impacts on public health. Some examples discussed in this paper
are higher indoor temperatures including extreme heat events; higher ozone levels and increased chemical
byproducts caused by chemical reactions with ozone indoors; increased outdoor pollution that raises
pollution levels indoors; reduced ventilation that saves energy but also increases indoor pollution
concentrations; increased moisture and humidity leading to indoor mold and other bio-contamination; and
ecological shifts leading to the increased spread of infectious diseases indoors.
Purpose
This report presents a preliminary analysis of the changes in indoor environmental quality likely to result
from changes in climate and assesses the potential public health consequences of those changes. To
determine how significant such changes might be from a public policy standpoint, the economic cost of
the public health consequences are also assessed. Although quantitative, the economic analysis is very
rough. It is intended only to help policy makers decide how important indoor environmental concerns
might be when setting priorities for further research or further policy exploration.
Organization of this Report
The report is organized as follows:
The Executive Summary briefly recaps the key points covered in each chapter and provides a
useful overview of the document.
3For example, EPA estimates that radon and environmental tobacco smoke are responsible for 24,000 premature
deaths (21,000 and 3,000 respectively) from lung cancer annually (EPA, 2003 and EPA, 1992). Indoor moisture and
mold are estimated to account for 21 percent (4.6 million) of asthma cases in the U.S. (Mudarri and Fisk, 2007) and
various aspects of indoor environmental conditions are estimated to result in annual lost productivity of $50 billion
to over $100 billion in non-industrial indoor environments (EPA, 1989 and Fisk, 2000).
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Chapter 1 presents a rudimentary framework for understanding the critical factors that determine
the indoor environmental quality of buildings in order to better understand how climate change
will affect indoor environments and associated public health consequences.
Chapter 2 discusses the impact climate change is expected to have on the outdoor environment,
focusing on the aspects most likely to have significant impacts indoors.
Chapter 3 discusses how changes in the outdoor environment brought about by climate change
will affect the indoor environment and lead to changes in the health, comfort, and productivity of
the public as they occupy their residences, schools, and commercial and institutional buildings.
Chapter 4 assesses the public health costs of the impacts discussed in Chapter 3.
Chapter 5 summarizes the impacts and discusses the implications for public and private actions
to protect the public health through improved indoor environmental planning and control.
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Chapter 1: Indoor Environmental Quality and Its Role in
Protecting Public Health
Chapter Overview
Before assessing potential indoor impacts of climate change in more detail, it is worthwhile to establish
the framework for understanding how the interrelationships between the outdoor environment, the
building, and occupant activities determine the quality of the indoor environment to which occupants are
exposed. This section provides a rudimentary framework for understanding the critical factors that affect
indoor environmental quality. It also establishes a framework for understanding methods to mitigate
negative impacts. Important features of the indoor environment and factors that affect them are
summarized in Table 1-1.
Table 1-1: Critical Factors Affecting Indoor Environmental Conditions
Indoor Environment
Critical Factors
Indoor Climate
Outdoor Climate
Indoor Temperature
Air change rate
Indoor Humidity
HVAC systems
Indoor Pollution
Outdoor pollution
Chemical
Air change rate
Particle
Ventilation
Biological
Exhaust
Indoor climate
Emissions from indoor sources
Indoor chemistry
Filtration and air cleaning
Moisture control
Indoor Temperature and Humidity
Indoor temperature and humidity are important to health. Higher temperatures and increased humidity in
buildings (e.g., the high end of the thermal comfort zone) have been associated with increased discomfort
and the perception of poor indoor air quality, increased occupant complaints, reduced productivity, and
adverse respiratory health symptoms. But prolonged exposure to excessive heat well beyond the comfort
zone, as predicted in climate change scenarios, can be a substantial health hazard. The ability of buildings
to mitigate the indoor heat and moisture impacts of climate change, particularly for susceptible
populations, is therefore a concern. Which buildings are vulnerable and in what regions of the country is a
subject worthy of investigation.
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Indoor Pollution
General Pollution Processes
The building itself, its furnishings and equipment, and its occupants and their activities produce pollution.
In a well-functioning building, some of these pollutants are directly exhausted to the outdoors and some
are removed as outdoor air is brought into the building displacing the air already inside. (However, the
outside air may also bring in pollutants.) This air exchange is brought about by mechanical ventilation
systems, by the natural infiltration and exfiltration of air through the building envelope, and from open
windows and doors.
Pollutants inside can travel through a building as air flows from areas of higher atmospheric pressure to
areas of lower atmospheric pressure. Some of these pathways are planned and deliberate to draw
pollutants away from occupants, but problems arise when unintended flows draw contaminants into
occupied areas.
Some contaminants may be removed from the air through natural processes, such as the adsorption of
chemicals by surfaces or the settling of particles onto surfaces. Air filtration and cleaning devices also can
remove some airborne contaminants.
Outdoor Air Ventilation, Energy, and Health
Ventilating indoor spaces has long been the primary means of removing pollutants generated indoors. By
replacing polluted indoor air with outdoor air, contaminant concentrations from indoor sources are
diluted.
In a space with a constant outdoor air ventilation rate and clean outdoor air, introducing a pollutant source
with a constant emission rate would make the air concentration gradually rise and approach a steady state
concentration. The steady state concentration will be proportional to the emission rate and inversely
proportional to the outdoor air ventilation rate.4 This rudimentary relationship demonstrates the
complementary roles that reducing emissions from indoor sources (source control) and providing
adequate outdoor air ventilation play in protecting public health by controlling exposure to indoor air
pollutants.
Prior to World War II, buildings were built with envelopes that "breathed," and operable windows
provided additional ventilation to occupants when needed. Opening and closing windows also helped
regulate indoor temperatures. Modern buildings, however, are constructed of less porous materials; air
conditioning is now widely used and mechanical ventilation has largely replaced operable windows in
large buildings.
In the U.S., the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE)
is the pre-eminent standard-setting authority with regard to ventilation rates for indoor-air-quality
purposes. ASHRAE Standard 62, Ventilation for Acceptable Indoor Air Quality, is used throughout the
building industry and is widely incorporated in state and local building codes.
4The steady state equation is simply Css = S/Q, where Css is the steady state concentration, S is the generation rate
of the indoor source (volume or mass per time unit), and Q is the outdoor air ventilation rate (volume per time unit).
This equation assumes no sink effects or indoor chemical reactions that would remove the contaminant from the
space.
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Inadequate ventilation is commonly found to be the primary reason for occupant complaints of poor
indoor air quality.
Indoor Chemical Reactions
As ozone and other smog-related reactive chemicals enter a building, they can react with compounds
found on the surfaces of commonly used building materials and furnishings and in cleaning products and
other surface treatments, air fresheners, and other products to produce carcinogens and irritants such as
formaldehyde, acrolein, other aldehydes, acids, and ultrafine particles that are often more toxic than the
original constituent compounds (Weschler, 2000, Nazaroff and Weschler, 2004). The impact of these
chemicals on public health can potentially be quite significant. It has been suggested that epidemiological
studies demonstrating increased mortality and morbidity during smog episodes outdoors may reflect the
health consequences of these secondary byproducts that result from indoor chemical reactions (Weschler,
2006). Knowledge in this field is rapidly emerging, but the true health impacts are not yet well
understood.
Compared to outdoors, the amount of indoor surfaces available to form reactive byproducts is extremely
large relative to building volume, and the residence time for reactions to occur is extended by surface
sorption (Morrison, 2008). Furthermore, indoor exposures to reactive byproducts of ozone is estimated to
be 2/3 to 6 times higher than exposures to ozone outdoors (Weschler, 2006).
Biocontamination and Other Moisture-Related Pollutants
Indoor biocontaminants include mold, dust mites, and allergens from cockroaches, rodents, and other
pests. Biocontaminants can trigger allergies, asthma attacks, and other respiratory conditions. High
humidity indoors can condense on cool surfaces and cause mold contamination. This is especially a
problem when the condensation occurs in hidden locations such as inside walls. Basements are commonly
damp and result in mold growth. Dust mites also require minimum humidity levels to survive, and
cockroaches are more likely to be found in damp areas.
There are many sources of excess moisture that can lead to biocontamination. They include high humidity
and condensation, wet conditions from spills, flooding, or poor drainage of rainwater; leaks in the
building envelope or from water pipes; and poor drainage of HVAC condensate.
The Role of Building Operation and Maintenance
A rigorous and adequately funded building maintenance program is fundamental for maintaining good
indoor environmental quality in schools, hospitals, and other institutional buildings and in residential and
commercial structures. Inadequate attention to and funding of operation and maintenance (O&M)
budgets and poorly trained personnel often lead to malfunctioning or contaminated HVAC systems that
result in inadequate ventilation and contaminated ventilation air, poor moisture control leading to
biocontamination, or the unintentional introduction of pollutants from sources such as improperly used
cleaning products. There is ample evidence of the association between common maintenance shortfalls
and reduced health and productivity in buildings (Mendell 2003; Wargocki et al., 2002b; Cole et al.,
1994; Raw etal., 1993).
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Indoor Environmental Quality and Public Health
Overview5
Indoor environmental quality affects individuals' thermal, olfactory, or sensory comfort; health; and work
performance. A broad range of health effects may result from exposure to indoor pollutants. Some
pollutants (e.g., radon, environmental tobacco smoke [ETS], formaldehyde, benzene, and
perchlorethylene) increase the risk of cancers or of other very serious health effects. Some indoor
pollutants can cause infectious diseases such Legionnaires' disease, the common cold, and influenza.
Allergy or asthma symptoms may result from exposure to indoor pollutants, especially biological
contaminants such as mold and plant or pest allergens. Finally, indoor pollutants may contribute to
irritation of the eye, nose, throat, or skin; coughing; wheezing; headache; and fatigue, symptoms that are
often called sick building syndrome (SBS) symptoms or building-related symptoms (BRS).
lust as indoor conditions affect people's health and comfort, indoor exposures also affect their
performance and productivity. The ability to perform mental and physical tasks, rates of absenteeism,
performance at school, and productivity at work have all been associated with indoor environmental
quality
A quick summary of some indoor environmental issues is provided below. How these issues could be
affected by climate change, if at all, is covered in later chapters.
Environmental Tobacco Smoke and Radon
ETS exposure: In 1992, EPA published its ETS risk assessment and declared ETS to be a class A human
carcinogen responsible for approximately 3,000 deaths each year from lung cancer and 150,000 to
300,000 lower respiratory tract infections (LRI) in infants and children under 18 months of age, resulting
in 7,500 to 15,000 hospitalizations (EPA, 1992). The report did not cover the effects of ETS exposure on
heart disease. However, in 2005 the California Air Resources Board (CARB) provided updated
information on the health impacts of ETS exposure for both California and the U.S., including estimates
for heart diseaseamong them an estimate of 46,000 premature heart disease deaths each year from ETS
exposure, plus other impacts on children.
Radon exposure: Radon is a colorless, odorless radioactive soil gas that enters buildings (mostly homes)
through cracks and crevices in the foundation. The surgeon general has warned that radon is the second
leading cause of lung cancer in the United States today; only smoking causes more lung cancer deaths.
The risk of lung cancer for smokers exposed to radon is especially high. According to EPA (2003), radon
is estimated to cause about 21,000 lung cancer deaths per year.
5The U.S. Environmental Protection Agency and the Lawrence Berkeley National Laboratory recently established an
Indoor Air Quality Scientific Findings Resource Bank (SFRB) that has begun to summarize current knowledge of the
public health impacts from indoor environmental conditions. While the subject matter covered thus far is limited to
just a few areas, information available from this resource includes the health and economic impacts of building
ventilation, the impacts of indoor environments on human performance and productivity, the effect of dampness and
biological pollutants on health, and volatile organic compounds and health. This site provides a more detailed
summary of some of the information covered in this section. The SFRB is available at
http://www.iaascience.lbl.gov/sfrb.html. Another excellent source of general scientific information on some indoor-
air-quality-related topics is Spengler, et al. (2001).
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Exposure to Volatile or Semi-Volatile Organic Compounds6
Numerous volatile organic compounds (VOCs) can cause sensory irritation symptoms when airborne
concentrations are sufficiently high, but, the evidence for sensory irritation at typical concentrations
indoors is very mixed and uncertain. However, taken together, mixtures of VOCs from certain products
such as water-based paints (Ten Brinke et al., 1998) and photocopiers (Apte and Daisey, 1999) or from
typical indoor conditions (Molhave et al., 1986) can cause sensory irritation at levels typically found
indoors, but this is not true for all mixtures.
The evidence is stronger that VOCs at concentrations found indoors can cause asthma-like respiratory
symptoms (Cal EPA, 2007; Mendell, 2007) though more research is needed. Formaldehyde is a common
compound found indoors, and it is not unusual for formaldehyde levels to exceed 8-hour exposure levels
for sensory irritation (Hodgson and Levin (2003), particularly in new homes, mobile homes, or portable
classroomsalthough levels do typically exceed thresholds for asthma-like respiratory symptoms, which
are lower.
Cancer: Many VOCs found indoors have been designated by multiple authorities as posing a risk for
cancer from long-term exposure. Table 1-2 identifies typical sources of VOCs having the highest
estimated cancer risks, which range from 1 in 1,000 to 1 in 100,000 from long-term exposures.
Table 1-2: Typical Sources of VOCs
VOC
Examples of Indoor Sources
formaldehyde
some manufactured wood products used as building materials, in cabinets, and in
furniture (e.g., medium density fiberboard, particle board, plywood with urea
formaldehyde resin; urea-formaldehyde foam insulation [no longer used but still
present in some buildings]); tobacco smoking; ozone-initiated chemical reactions
with common indoor VOCs, unvented combustion appliances
napthalene
pesticides (moth balls)
paradichlorobenzene
pesticides (moth crystals); toilet bowl deodorizer
chloroform
pesticides; showering; washing clothes and dishes
acidaldehyde
tobacco smoke; water-based paint; unvented combustion appliances; leakage
from wood stoves, furnaces, and fireplaces; (outdoor air also an important
source)
benzene
tobacco smoke; some furnishings, paints, coatings, wood products, gasoline from
attached garages (outdoor air also an important and sometimes predominant
source)
Source: LBNL (undated)
6See the IAQ Scientific Findings Resource Bank (SFRB) for a more detailed discussion. Available at
http://www.iaqscience.lbl.gov/sfrb.html).
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Sick Building Syndrome and Human Performance and Productivity7
In addition to specific health endpoints, many characteristics of indoor environments are related to a
number of non-specific health complaints generally referred to as Sick Building Syndrome (SBS). These
include, for example, nasal and sinus congestion, headache, runny nose, dry or itchy eyes, sore throat,
lethargy, and dizziness. These same characteristics are also related to changes in various measures of
human performance and productivity. Characteristics of particular interest include ventilation rate,
temperature, the presence of indoor sources of VOCs, the presence of particles on surfaces or the degree
of cleaning, and maintenance of HVAC systems. While productivity effects may be a direct result of
changes in these indoor environmental conditions, it is also likely that some form of degradation of health
or comfort acts as an intervening factor affecting productivity. For this reason, issues of productivity are
discussed in the same context as SBS in this report.
Ventilation: Since inadequate ventilation increases the concentrations of all contaminants generated
indoors, much of the evidence that poor indoor environmental quality increases SBS symptoms and
reduces productivity is related to inadequate ventilation rates. The evidence is very strong and repeated in
multiple studies. For example, in a major review article, Seppanen et al. (1999) wrote that ventilation
studies report relative risks of 1.5 - 2.0 for respiratory illnesses and 1.1-6.0 for SBS symptoms when
comparing low to high ventilation rates. Almost all studies found that ventilation rates below 10 L/s (20
cfrn) per person were associated with statistically significant worsening of health or perceived indoor air
quality (IAQ) outcomes. Similarly, Seppanen and Fisk (2006) conducted statistical analyses from a
number of studies relating office ventilation rates with performance and found a monotonic relationship
between ventilation rate and productivity. In addition, various aspects of schoolwork (Wargocki and
Wyon, 2007, 2007a), possibly including test scores (Shaughnessey et al., 2006), have been shown to
improve with higher ventilation rates.
Inadequate ventilation has also been shown to increase absenteeism in offices (Milton et al., 2000; Myatt
et al., 2002) and schools (Shendell et al., 2004).
Air conditioning: Seppanen and Fisk (2002) reviewed multiple studies and reported that relative to
natural ventilation, air conditioning with or without humidification was consistently associated with a
statistically significant increase in the prevalence of one or more SBS symptoms. This occurrence is most
likely related to the fact that air conditioning involves collecting moisture within the ventilation system,
which can foster biocontamination. That conclusion was confirmed by a multidisciplinary team of
scientists that also reported increased SBS symptoms with inadequate HVAC maintenance (Wargocki et
al., 2002b).
Effect of VOC sources: The presence of known indoor sources of VOCs has been shown to decrease
various measures of work performance. They include a 20-year-old carpet from a complaint building
(Wargocki et al., 2002a), personal computers equipped with cathode ray monitors (Bako-Biro, 2004), and
a 6-month-old particle filter (Wargocki et al., 2004). Although VOCs were not measured in these studies,
these items are known sources of VOCs, and the results are consistent with other studies showing
improved performance with increased ventilation.
Ibid.
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Moisture-Related Biocontamination
Damp buildings tend to support the growth of mold and bacteria on indoor surfaces. Spores and other
fragments released by this microbial growth becomes airborne and subject to being inhaled. The particles
often contain allergens, creating adverse health consequences in people who experience an allergic
response. In addition, molds and bacteria produce toxic chemicals that have the potential to adversely
affect immune or central nervous system functions or produce musty odors.
Dust mites, which are microscopic arthropods, release allergenic particles in the air and feed on skin
flakes and other organic material. They are often found in bedding and upholstered furniture. Since dust
mites absorb rather than drink water, they depend on a relative humidity above approximately 50 percent
to survive (Hart, 1998); Arlian et al., 1999).
Approximately 47 percent of homes are estimated to be sufficiently damp to result in respiratory affects in
those exposed and are estimated to be responsible for 21 percent of current asthma cases in the U.S.
(Mudarri and Fisk, 2007). Moisture and dampness in schools and office buildings are also associated with
respiratory effects in occupants (Mudarri and Fisk, 2007).
Communicable Respiratory Diseases
Building O&M procedures can affect disease transmission in buildings. For example, lower ventilation
rates and improper airflow directional control may lead to higher airborne disease transmission
particularly in hospitals, schools, and other high-occupant-density buildings such as barracks.
Transmission may also occur through contact, either direct contact with infected persons or indirect
contact by touching common surfaces such as doorknobs, drinking fountains, phone handles, and
computer key boards. Policies that encourage the isolation of infected individuals (e.g., telecommuting
when sick) and building maintenance practices (e.g., clean and disinfect common surfaces regularly) can
help limit transmission, as can avoidance of overcrowded conditions. The potential for disease vectors
(e.g., rodents, insects, arthropods, birds, fungi) to enter and proliferate in buildings can be mitigated by
blocking their entry points, minimizing their dispersal potential, removing their access to food and water,
minimizing areas of potential harborage, and undertaking similar "integrated pest management (IPM)"
maintenance activities.
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Chapter 2: Climate Change Impacts on the Outdoor
Environment
Chapter Overview
This chapter provides an outline summary of climate change impacts on the outdoor environment,
focusing on the aspects that have the greatest implication for altering indoor environmental quality. The
chapter covers both gradual and episodic impacts For example, a gradual rise in mean temperature or
precipitation will be accompanied by episodic extreme weather events such as heat waves, storms, and
heavy precipitation that are expected to be more intense and occur more frequently.
Summary Outline of the Impacts of Climate Change on the Outdoor
Environment
A recent U.S. government report (USGCRP, 2009) provides a useful summary of anticipated impacts of
climate change. Major findings relevant to indoor environmental quality are paraphrased below.
Mean Temperature Will Rise
The global warming observed over the past 50 years is due primarily to human-induced emissions
of heat-trapping gases.
Warming over this century is projected to be considerably greater than over the previous century.
The global average temperature since 1900 has risen by about 1.5 °F. It is projected to rise
another 2 to 11.5 °F by 2100. By the end of this century, the average U.S. temperature is projected
to increase by approximately 7 to 11 °F under high emissions scenarios and approximately 4 to
6.5 °F under low emissions scenarios.
The U.S. average temperature has risen by a comparable amount and is very likely to rise more
than the global average over this century, with some variation from place to place.
Increases at the lower end of the range are more likely if global heat-trapping gas emissions are
cut substantially. If emissions continue to rise at or near current rates, temperature increases are
more likely to be near the upper end of the range
Humidity and Drought Conditions Will Change
Atmospheric conditions in northern regions will change from very cold and dry to warmer and
more humid. Alaska, the Great Plains, the upper Midwest, and the Northeast are beginning to
experience such changes for at least part of the year, and it is likely these changes will increase
overtime.
Droughts are likely to become more frequent and severe, particularly in the Southwest.
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Heat Waves Will Be More Frequent, More Intense, and Last Longer
Parts of the South that have about 60 days per year with temperatures over 90 °F are projected to
experience 150 or more days a year above 90 °F by the end of this century.
Heat events that now occur once every 20 years are projected to occur about every other year in
much of the country by the end of this century.
In addition to occurring more frequently, at the end of this century these very hot days are
projected to be about 10 °F hotter than they are today.
The number of heat-wave days in Los Angeles is projected to double by the end of this century
and the number in Chicago is projected to quadruple if greenhouse gas emissions are not reduced.
Heavy Precipitation Events Will Increase in Intensity
Precipitation has increased an average of about 5 percent over the past 50 years. Projections of
future precipitation generally indicate that northern areas will become wetter and southern areas,
particularly in the West, will become drier.
The amount of rain falling in the heaviest downpours has increased approximately 20 percent on
average in the past century, and this trend is very likely to continue with the largest increases in
the wettest places.
Widespread increases in heavy precipitation events have occurred, even where total rain amounts
have decreased. These changes are associated with the fact that warmer air holds more water
vapor evaporating from the world's oceans and land surface.
Heavy downpours that are now l-in-20-year occurrences are projected to occur about every 4 to
15 years by the end of this century, depending on location.
The intensity of heavy downpours is expected to increase. The l-in-20-year heavy downpour is
expected to be between 10 and 25 percent heavier by the end of the century.
Storms Will Likely Become More Intense
Hurricanes
The destructive energy of Atlantic hurricanes has increased in recent decades. The intensity of
these storms is likely to increase in this century.
In the eastern Pacific, the strongest hurricanes have become stronger since the 1980s, even while
the total number of storms has decreased. However, storms in this region that reach land are rare
compared to those that reach landfall along the East Coast and Gulf Coast of the United States.
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Snowstorms
Cold-season storm tracks are shifting northward, and the strongest storms are likely to become
stronger and more frequent if that northward shift continues as projected. The stronger, more
frequent cold-season storms also are likely to result in greater wind speeds and more extreme
wave heights in northern areas (e.g., the Northeast and upper Midwest).
Lake-effect snow storms in the Great Lakes region are likely to increase (less ice coverage
induces greater lake evaporation and hence heavier snow fall) causing potentially heavy snow
storms such as that experienced in February 2007 in western New York State.8
Sea Level Will Rise
Global sea levels will rise due to glacier melting and water expansion due to warming. However,
geological forces may cause coastlines to sink (subsidence) or rise (uplift), creating differential
impacts.
During the past 50 years, large parts of the Atlantic Coast and Gulf Coast have experienced
significantly higher rates of relative sea level rise than the global average due to subsidence.
However, portions of the Northwest and Alaska coasts have experienced slightly falling sea level
as a result of long-term uplift.
Assuming historical geological forces continue, a 2-foot rise in global sea level (within the range
of recent estimates) by the end of this century would result in a relative sea level rise of 2.3 feet at
New York City, 2.9 feet at Hampton Roads, Va, 3.5 feet at Galveston, Texas, and 1 foot at Neah
Bay in Washington State.
Sea level rise will increase risks of erosion, storm surge damage, and flooding for coastal
communities, especially in the Southeast and parts of Alaska.
Forest and Grass Fires Will Be More Frequent and More Widespread
In western United States and Alaska, earlier snowmelt and higher spring and summer
temperatures have increased the frequency of large fires and extended the fire season as these
conditions reduce available moisture. This trend is expected to continue.
Deserts and dry lands in the arid Southwest and elsewhere have become hotter and drier, and this
trend is expected to continue. Deserts are also projected to expand to the north and east, and
upward in elevation.
Increased drought conditions have and will continue to encourage non-native grasses to invade
the Southwest and will provide fuel for fires, which are expected to increase in frequency and
intensity.
8However, the heavy precipitation is projected to eventually fall as rain rather than snow with increased warming in
the long term.
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Pathogenic and Allergenic Diseases May Increase with the Potential for Mass
Outbreaks
Longer and warmer growing seasons with less extreme cold in winter creates opportunities for
many parasites and disease-carrying insects to flourish.
For some species, rates of reproduction, population growth, and biting tend to increase with
increasing temperatures. Some parasites' development rates and infectivity periods also increase
with temperature.
Unforeseen ecological changes could result in massive dislocations of species or in pest
outbreaks.
With global trade and travel, disease flare-ups in any part of the world, particularly in poorer
nations, brought about by climate change can potentially reach the United States, where extreme
weather events could undermine public health infrastructure, creating increased population
vulnerability.
Rising temperatures and carbon dioxide concentrations increase pollen production and prolong
the pollen season in a number of plants with highly allergenic pollen, presenting a health risk.
With stresses on infrastructures related to public health, disease transmission from food, water,
and insects is likely to increase.
Outdoor Air Quality Will Worsen
A warmer climate is projected to increase the natural emissions of VOCs, accelerate ozone
formation, and increase the frequency and duration of stagnant air masses that allow pollution to
accumulate.
Increased temperatures and water vapor due to human-induced carbon dioxide emissions have
been found to increase ozone more in areas where concentrations are already elevated, meaning
that global warming tends to exacerbate ozone pollution most in already polluted areas.
With constant pollutant emissions, Red Ozone Alert Days (when the air is unhealthy for
everyone) in the 50 largest cities in the eastern United States are projected to increase by 68
percent due to warming alone, by the middle of this century.
Infrastructure Will Be Damaged and Adaptation Made Difficult
The projected rapid rate and large amount of climate change over this century will challenge the
ability of society and natural systems to adapt. For example, it is difficult and expensive to alter
or replace infrastructure designed to last for decades (such as buildings, bridges, roads, airports,
reservoirs, and ports) in response to continuous or abrupt climate change.
Adaptation will be particularly challenging because society will be adapting to a rapidly moving
target, not to a new steady state. Climate change will be continual and occur at a relatively rapid
rate, outside the range to which society has adapted in the past.
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Chapter 3: Impacts of Climate Change on Indoor
Environmental Quality and Implications for Public Health
Chapter Overview
This chapter couples the impacts of climate change on the outdoor environment from Chapter 2 with the
factors that influence indoor air quality from Chapter 1 to characterize the likely impacts of climate
change on indoor environmental quality. The material covered in Chapters 1 and 2 are delineated in more
detail as needed to more fully characterize these impacts of climate change.
Impacts of Climate Change on Indoor Temperature and Outdoor Air
Ventilation
Overview
In the absence of a wise policy or other social intervention, it is likely that increased outdoor
temperatures, rising energy prices, and the need to reduce greenhouse gas emissions will foster a cycle of
self-reinforcing behavior changes that will continually degrade indoor environmental quality. Higher
indoor temperatures and humidity will increase use of air conditioning and substantially increase
electricity demand. However, increased generation of electricity increases emissions of greenhouse gases,
which accelerate the trend toward rising temperatures. Countering this trend toward greater electrical
generation are the substantial disruptions to power generation and distribution created by other climate
change impacts, particularly during extreme weather events. Both factorsincreased demand and
interruptions in supplyare expected to raise energy prices and result in unmet needs for cooling indoor
environments. Higher energy prices and the desire to limit greenhouse gas emissions will likely
encourage individuals and public policy toward greater energy conservation through reduced ventilation
in buildings. Less comfort, reduced productivity, and increased SBS symptoms are likely to result.
The Importance of Temperature Control for Good Indoor Environmental
Quality
It is well known that exposure to extreme temperatures, especially for extended periods, can have
significant health consequences. Less well known is how important temperature control in the mid-
temperature range is for comfort and productivity, although complaints of it being "too hot" or "too cold"
are the most frequently logged complaints in commercial buildings.
Moderately high temperatures have been associated with poorer perceptions of indoor air quality
(Bergland and Cain, 1989; Fanget al, 1998) and with higher rates of unsolicited occupant complaints
(Federspiel, 1998). Poor perceived indoor air quality (as well as temperature itself) are in turn also
associated with SBS and lost productivity (Seppanen and Fisk, 2005). In addition, there is evidence of
increased respiratory effects resulting from higher temperatures. This was a surprising but predominant
effect measured in a study of the affect of particles on office workers (Mendell et al., 2002).
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The importance of temperature control on productivity is summarized in LBNL (undated), in which a
formal statistical analysis of 24 studies (Seppanen et al., 2005) was used to assess the average relationship
between temperature and performance of work. While there may be considerable uncertainty in
generalizing specific productivity figures, the LBNL analyses show an "inverted U" shaped relationship
in which productivity is generally highest when the air temperature is in the midrange of approximately
68 - 72 °F and falls continuously as the temperature deviates from that range in either direction, so that at
59 °F and 87 °F, productivity is diminished by 10 percent from the maximum. Since wages in general are
approximately 100 - 200 times building operating costs in office buildings, it makes economic sense to
invest in building maintenance or upgrades as needed to maintain occupant productivity.
Thus, it is not only important for public health to protect occupants from extreme heat, it is also important
for economic reasons to maintain temperatures at moderate levels where occupants are comfortable and
productive. Certainly, any increase in temperatures beyond what is considered comfortable will increase
the demand for air conditioning and, consequently, the demand for electricity. While there may be serious
questions about the nation's ability to satisfy power needs from increased air conditioning use during
extreme heat events (see below), the capacity of air conditioning systems themselves will likely be
strained in northern climates such as New England, where air conditioning penetration is still low; these
areas may experience the largest indoor environmental problems from the increase in mean climate
temperatures.
In addition, VOCs are released from materials and products inside buildings more rapidly at higher
temperatures. Thus, if occupants are too warm, it is likely they are also being exposed to higher levels of
indoor pollutants.
Indoor temperatures are controlled by the HVAC system. How well the temperature is controlled depends
on the capacity and operating parameters of the system and on the heat gains and losses in the space being
controlled. Indoor humidity conditions are analogous to indoor temperature as they depend on moisture
gains and losses and on the HVAC system's capacity to control humidity. Like heat, increased outdoor
humidity is also associated with climate change. Unlike heat, however, excess humidity carries the
potential for unintended condensation on cooled indoor surfaces, including hidden surfaces within the
building fabric, and thereby creates conditions conducive to mold growth and other forms of
biocontamination.
All of these considerations raise the issue of whether building O&M in the U.S. will be adequate to
maintain appropriate indoor climate conditions. As is discussed below, this issue may be highly
problematic given the presence of climate change and the lack of a clear focus on indoor air quality by
climate change policy. One encouraging sign is that many buildings in the U.S. may currently be
overcooled (Mendel and Mirer, 2009) leaving room for increased outdoor temperature conditions to
increase indoor temperatures without extra cooling.
The Impact of Heat Waves on Indoor Environments
Of more acute concern is the likelihood that heat waves will increase in frequency and intensity. The
frequency of extremely high temperatures (e.g., above the current 90th percentile) is likely to increase
more dramatically than median or average temperatures. This situation is best illustrated by the bell shape
of a temperature distribution curve, as shown in Figure 3.1.
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Heat waves are an important public health threat. When the body is stressed in its ability to maintain
internal thermal control, heat cramps, heat exhaustion, and heat stroke, in order of severity, can be the
result. A variety of other adverse health conditions can also result. They include painful muscle cramps,
dizziness, fainting, nausea and vomiting, heavy sweating, rapid pulse, high body temperature, and
unconsciousness. Mortality rates during heat waves can also increase substantially. Populations that are
likely to suffer most from excess heat include the elderly, very young infants,, and those taking certain
medications or under the influence of daigs or alcohol. Persons with impaired mobility or mental
disabilities may be less able to find coool environments. Low-income individuals are also vulnerable due
to the lack of medical services and limited opportunities to keep cool (EPA, 2006).
The number of deaths from extreme heat can be quite high. For example, during the 2003 heat wave in
Western Europe, France alone experienced over 15,000 deaths. In the United States, Philadelphia
experienced 120 deaths from the 1993heat wave in, while 700 deaths in Cook County Illinois were
attributed to the 1995 heat wave.
Figure 3.1: Impact of Gradual Temperature Increases on Extreme Temperature Events
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These recommendations do not address the structural issues of equipping indoor environments to shelter
the population during such events. Serious disruption to people's lives and to the economy will likely
result as a consequence of the inability of buildings to perform their most basic function: to shelter people
from the outdoor environment and to provide healthy and productive living environments. Cooling indoor
environments from excessive heat is a public health issue that will call for increased use of air
conditioning, but there are serious problems that the nation will likely face in trying to satisfy that public
health need.
Ability to Satisfy Increased Demand for Air Conditioning May Be Severely
Constrained
Impact of Mean Temperature Rise on Electricity Demand and Supply
The gradual increase in outdoor temperatures, which are expected to rise by 4 - 11 °F by the end of the
century, will call for substantial increases in air conditioning. How much of an increase can be measured
in part by changes in the number of cooling degree-days expected in different regions.
A recent U.S. government report (USGCRP, 2009a) provides a useful summary of research in this area9.
Figure 3.2, taken from that report, shows how cooling degree-days are expected to increase, while heating
degree-days are expected to decline as a result of climate change. Since cooling uses electricity while
heating uses mostly natural gas and little electricity, the demand for electricity is expected to increase.
Research on the impact of climate change on energy use suggests that the demand for cooling energy
increases from 5 percent to 20 percentand the demand for heating energy drops by 3 percent to 15
percentfor every 1 °C (1.8 °F) increase in outdoor temperature. This change would translate to a 10-
percent to 120-percent increase in electricity use by the end of the century, assuming current technology.
These studies do not account for the increase in energy used by air conditioning to remove the excess
moisture that is also expected to accompany climate change, so that this is a conservative estimate. On the
other hand, it is highly likely that greater efficiencies will be achieved over time and that some "natural
conditioning" using different construction techniques to keep buildings cool will be employed.
Nevertheless, significant increases in electricity demand for cooling can be anticipated, which in turn will
create a corresponding demand for increased electric power generation and increased power generation
capacity. The demand for electricity to power air conditioning will exceed the capacity to generate that
electricity in areas where the ability to maintain cool indoor temperatures is particularly problematic.
Stresses on power generation could be substantial. For example:
9This section borrows heavily from the analysis in this report.
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Shifting Energy Demand in the United States
Cooling Degree Days
Hislcrca
Lcwe' emiss ons
scalane'
Highe' enissiDns
scenario1
Heatng Degree Days
Histcrci
Lower enissions
scenario'
Higher e nissions
scenario'
New York
Chicago
Dallas
Los Angeles
CMIP3-B ¦
"Degree days" are a way of measuring the energy needed for heating and cooling by adding up how many degrees
hotter or colder each day's average temperature is from 65CF over the course of a year. Colder locations have
high numbers of heating degree days and low numbers of cooling degree days, while hotter locations have high
numbers of cooling degree days and low numbers of heating degree days. Nationally, the demand for energy
will increase in summer and decrease in winter. Cooling uses electricity while heating uses a combination of
energy sources, so the overall effect nationally and in most regions will be an increased need for electricity.
The projections shown in the chart are for late this century.
Source: USGCRP (2009a)
Stresses from water shortages: It is likely that water shortages will limit power production in many
regions. Electricity production uses almost as much fresh water as irrigation in the U.S. Water shortages
in parts of the South (Florida, Louisiana, Georgia, Alabama), parts of the Southwest (Arizona, Texas),
and the West/Northwest (Utah, California, Oregon, and Washington State) are expected to constrain
electricity production. These and other areas where demand for water increases due to drought, expanding
populations, or other reasons may also find it difficult to increase electricity production. Energy will also
be needed to move and manage water resources during these scarcities, further straining the availability of
electnc power to satisfy air conditioning demands.
Hydropower generation is sensitive to the amount of water available and the timing of its availability.
Changes in water availability patterns from climate change could therefore significantly hinder
hydropower generation and affect areas such as the Northwest, where hydropower is a significant source
of electricity. Changes in the timing and amount of flow have already been experienced due to reduced
snowpack, melting glaciers, and earlier peak runoff. This trend is expected to continue. In addition,
wanning is expected to cause more rapid evaporation of reservoirs, particularly in sunny arid areas. Thus,
the availability of electricity to fully satisfy indoor environmental needs in these areas is problematic.
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Stresses from sea level rise: A good deal of the U.S. energy infrastructure is located in coastal areas,
particularly along the East and Gulf Coasts. These areas are particularly vulnerable to sea level rise
because of their topography., They also are subject to hurricanes. Electric power plants in these areas are
vulnerable, as plants that process natural gas, which is used for electricity generation. Approximately 20
percent of natural gas production is located in the Gulf Coast region. Sea level rise in the Gulf is expected
to reach as high as 2 - 4 feet by the end of the century. In addition to sea level rise, major hurricanes and
storm surges can wreak havoc on these facilities, as was experienced during Hurricane Katrina.
Stresses from extreme weather events: Extreme weather events could lead to dramatic increases in
peak demand for electricity that result in long-lasting supply interruptions. For example, as the average
temperature increases, the frequency of what are currently considered extreme temperatures increases
dramatically. These are the times of peak demand,10 when existing energy infrastructure is strained to
meet demands for cooling. It is expected, therefore, that the frequency of events where power is not
available to satisfy indoor environmental quality needs will dramatically increase.
In addition to extreme temperatures, heavy rains and local flooding can interrupt coal transport to power
plants via rail that often follow riverbeds in the Appalachian region. Extreme weather events including
heavy rains and snowstorms, which are predicted to increase in intensity, can damage the power grid over
large areas of the country. For example, the number of significant weather-related disturbances in the U.S.
electric grid has increased tenfold since 1992. These disturbances do not include local disturbances from
downed power lines, which cause the majority of power interruptions to end users and may also be
expected to increase.
The Shift from Heating to Air Conditioning Increases Greenhouse Gas
Emissions
The residential and commercial building sectors' use of energy accounts for approximately 38 percent of
the carbon emitted to the atmosphere in the U.S. (9 percent of global fossil fuel-related emissions). These
emissions are predicted to rise by 50 percent by 2030, absent any impact from climate change. However,
climate change will exacerbate this trend, as the major energy needs in buildings shift away from heating,
where natural gas is the major fuel source, to air conditioning, which uses electricity generated to a large
extent by burning coal. Since about 50 percent of electricity is generated by burning coal, a high-carbon
fuel, and since it takes over 3Btu of energy input for every Btu of delivered electric energy (including
transmission losses), the shift in energy usage toward electricity will increase C02 emissions in what
amounts to a potentially destructive negative feedback loop.
Pressures for Reduced Ventilation to Reduce Energy Use are Likely
Given the large role that buildings play in greenhouse gas emissions and the potential for climate change
itself to foster even greater emissions, there is little doubt that the building sector will be called upon to
reduce energy usage. This, too, will likely place great stress on indoor environmental quality with
significant public health consequences, as described below.
1'Increases in peak energy demand would require a disproportionate increase in energy infrastructure investment
(Scott, et al.). Linder and Inglis (1989) predicted that between 2010 and 2055, climate change could require
investments of $200 billion - $300 billion ($1990).
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Reducing Ventilation Saves Energy
While there are some important misconceptions about the energy cost of ventilation, there is no denying
that reducing ventilation rates can significantly reduce energy use during outdoor temperature extremes
because of the expense of treating outdoor air to satisfy indoor thermal requirements. The opposite may
be true, however, during mild weather when the outdoor air is closer to the desired indoor conditions than
is the existing indoor air. 11
Historically, the challenge to reduce energy use in buildings has been met, in part, by reducing outdoor air
ventilation rates. For example, as energy prices rose during the 1970 Arab Oil Embargo and the desire to
save energy became widespread, building envelopes were tightened, much more energy efficient windows
were introduced, and ventilation was curtailed to avoid having to use energy to "condition" the ventilation
air. In 1981, ASHRAE significantly reduced the required ventilation rates in buildings in response to
energy conservation needs. The result was a wave of occupant complaints and litigation about building-
associated illnesses.
Pollutant emissions indoors increase with the number of occupants because of the bio-effluents of
occupants and because of the emissions from the products that occupants use. Therefore, the ventilation
rates required for indoor air quality in buildings rises with increased occupant densities. Thus, schools and
other high-occupant-density buildings require higher ventilation rates than office buildings or homes, and
the per-square-foot energy costs for ventilation to maintain adequate indoor air quality in these buildings
will be considerably higher (Mudarri et al., 2000).
Economic and Public Policy Pressures to Reduce Ventilation Will Develop
The response to the energy crisis in the 1970s stands to be repeated in response to climate change unless
the public health consequences of indoor environmental quality receive far more attention. Because the
energy costs of ventilating high-occupant-density-buildings are high, schools and similar buildings are
particularly vulnerable to pressure to reduce ventilation rates. They also have the greatest financial
incentive to do so. This situation could create serious problems for school children. Climate change policy
would be wise to include provisions to reduce energy use while maintaining adequate ventilation for
indoor environmental quality.
Outdoor Air Ventilation and Public Health
In an occupied enclosed space without any ventilation, the concentration of pollutants emitted from
indoor pollutant sources, including people themselves, will continually rise to dangerous levels. This is
why outdoor air ventilation is so important to public health.
As discussed elsewhere, ventilation dilutes contaminants generated indoors so that, in general, pollutant
concentrations from indoor sources are inversely proportional to the outdoor air ventilation rate. This
fundamental fact is likely behind the previously described historical experience of the United States and
Europe, where reducing building ventilation rates in an attempt to save energy led to a sharp increase in
occupant complaints. Subsequent studies confirm the adverse effect of low ventilation rates on occupants.
For example:
nThe economizer operation of commercial HVAC systems uses the cooler outdoor air to help cool the indoor
environment without using air conditioning. This technique typically is called "free cooling."
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In homes, low ventilation rates are associated with increases in formaldehyde and VOCs (Emenius et al.,
2004), increased risk of bronchial obstruction caused by other conditions such as dampness (Oie et al.,
1999), increased allergy symptoms (Bornhag et al., 2005), and asthma (Emenius et al., 2004; Norback et
al., 1995).
In offices and schools, low ventilation rates are associated with degraded perceptions of indoor air quality
(Wargocki et al., 2000; Seppanen et al., 1999), increased symptoms of sick building syndrome (Seppanen
et al., 1999; Wargocki et al., 2002; Mendell,et al., 2005; and Fisk et al., 2009), increased absences
(Shendell et al., 2004; Milton et al., 2000), decreased performance and productivity (Wargocki et al.,
2002a, 2004; Bako-Biro et al., 2004; Seppanen et al., 2006), and decreased performance in school work
(Wargocki and Wyon, 2007, 2007a), possibly including reduced test scores (Schaunessey et al., 2006).
In high-occupancy buildings (nursing homes, barracks, jails), low ventilation rates are associated with
higher rates of respiratory illnesses (Seppanen et al., 1999; Brundage et al., 1988; Hoge et al., 1994;
Drinka et al., 1996) and, in hospitals, with increased transmission of infectious diseases (Li et al., 2005,
2007).
While scientific documentation of these effects is still emerging, taken together, available evidence
provides a compelling case for maintaining ventilation rates in buildings as a matter of public health.12
Ventilation Strategies to Protect Indoor Environmental Quality Are Needed
Unless adaptation strategies are implemented, the warming and increased humidity brought about by
climate change will increase the energy cost of ventilating buildings, which is critical to maintaining good
indoor environmental quality. Such strategies could include increasing the energy efficiency of
equipment, employing ventilation strategies that use less energy (e.g., separating outdoor air delivery
from heating and cooling airflow requirements, or employing more natural ventilation13), adopting
ventilation strategies that are more efficient in removing contaminants (e.g., displacement ventilation,
increased exhaust ventilation), or strategically integrating more air cleaning into the ventilation system. In
addition, a major effort to reduce pollutant emissions from products and materials used in a building
would go a long way in reducing the need for ventilation in order to maintain adequate indoor air quality
to protect public health.
Some of these strategies, such as using displacement ventilation or natural ventilation, might be feasible
only in new building construction, while others, such as separating the outdoor air flow from heating and
cooling air flow requirements and more strategic use of exhaust ventilation, might be feasible through
expensive remodeling efforts. Still other strategies, such as increasing the energy efficiency of equipment
or incorporating ERVs or air cleaning devices might be implemented by retrofitting existing equipment.
Each of these strategies becomes more cost-effective as energy prices rise.
12See the IAQ Scientific Findings Resource Bank (SFRB), for a useful summary of this evidence. Available through
http://www.epa.gov/iaa/largebldgs/index.html or directly at http://www.iaascience.lbl.gov/.
13Natural ventilation makes building occupants particularly vulnerable to outdoor air pollution. This topic is
discussed separately in this report.
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Reducing Outdoor Air Ventilation during High Pollution Episodes
As indoor air is exchanged with outdoor air, the indoor concentration of a pollutant will eventually equal
the outdoor air concentration plus contributions from indoor sources. For this reason, it is often stated
that in the long run, the outdoor air acts as the background for indoor air pollution, to which emissions
from indoor sources are added. Thus, if climate change results in increased outdoor pollutant
concentrations over extended periods, this increased pollution will ultimately find its way indoors, unless
the outdoor ventilation air is cleaned prior to entering the building. Cleaning the air, however, will require
additional energy, so the relationship between ventilation, air cleaning, indoor air quality, and energy use
may become extremely important in developing strategies to protect public health from climate change.
If outdoor pollutant levels rise in episodic events, it is possible to lower the outdoor air ventilation rates
temporarily to protect the indoor environment. This strategy would take advantage of the fact that the
indoor concentration from indoor sources takes time to rise toward a new higher steady state level as the
ventilation rate is reduced.14 If the episode is brief, this strategy could be useful. The only other
alternatives would be to reduce indoor source emissions and provide additional air cleaning for both
indoor air and outdoor air. Additional air cleaning and reduced source emissions would each allow for
reduced ventilation rates while protecting indoor air quality.
Some outdoor contaminants have greater public health consequences than others. Ozone, for example, can
have particularly significant public health consequences indoors for a variety of reasons. But temporarily
reducing outdoor air ventilation to reduce ozone exposuremay not be advisable, as discussed below in the
section on indoor chemistry.
Indoor Chemistry Effects from Outdoor Ozone
Overview
Tropospheric ozone is the product of atmospheric chemistry in which reactive VOCs interact with oxides
of nitrogen in the presence of sunlight to produce photochemical smog, including ozone. Higher
temperatures contribute to this process by increasing the levels of ozone produced. Thus, climate change
is expected to increase tropospheric concentrations of ozone.
Ozone is known to react with many VOCs found indoors to create a variety of chemical byproducts that
have potentially troubling adverse health consequences. Emerging research suggests that with increased
ozone concentrations outdoors, the adverse health consequences from indoor chemical reactions could
present a significant unanticipated public health issue.
Increased Ozone from Climate Change
In a recently published study (EPA, 2009), EPA summarizing results from several modeling studies and
reported the following:
14Levels of outdoor pollution will ultimately become background levels of indoor pollution to which indoor
generated pollutants are added. If outdoor levels are constant, and the indoor emission rate is constant, and the
indoor air starts out with a zero contaminant level, the indoor air concentration of the contaminant will gradually rise
toward its steady state value, achieving 95 percent of the steady state value in h=3/ach where h = hours and ach is
the air change rate (see Mudarri, 1997). In a typical home with an air change rate of 0.5, 95 percent of steady state is
achieved in 6 hours. By lowering the ventilation rate so that ach is 0.33, the time is extended to 9 hours.
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Climate change has the potential to produce significant increases in near-surface ozone
concentrations throughout the United States.
For nearly every region of the country, at least one (and usually more) of the modeling groups
found that climate change caused increases in summertime ozone concentrations.
Where these increases occur, the amount of increase in the summertime average Maximum Daily
8-hour Average (MDA8) ozone concentrations across all the modeling studies tends to fall in the
range of 2 - 8 ppb.15
These results suggest a possible extension of the ozone season into the late spring and early fall in
some regions of the U.S.
Climate change has the potential to push ozone concentrations in extreme years beyond the
envelope of current natural year-to-year variability
A subset of results also suggests that climate change effects on ozone grow continuously over
time.
The largest increases in ozone concentrations in these simulations occur during peak pollution
events. (For example, the increases in the 95th percentile of MDA8 ozone tend to be significantly
greater than those in summertime-mean MDA8 ozone.)
That last point is particularly important. There is a strong relationship between temperature and the
conditions that produce high ozone levels. Thus, the severity of a particular ozone episode will depend
strongly on temperature and other meterological conditions (e.g., sunlight), many of which also tend to
correlate strongly with temperature. Thus, long periods of summer heat and drought will likely produce
high ozone concentrations, along with elevated levels of particulate matter, exacerbated in some regions
by pollution from forest fires, from higher levels of pollen, and from elevated carbon dioxide. Since the
rise in peak ozone levels is expected to be considerably more pronounced than the average rise, and since
high ozone concentrations also tend to occur when concentrations of other pollutants are high, episodic
events of high ozone concentrations will be of particular concern.
Indoor Chemical Reactions with Ozone
Recent studies have shown that indoors ozone can interact with chemical compounds in indoor air and on
surfaces to produce elevated levels of many toxic compounds, including formaldehyde, and of fine and
ultrafine particles that could potentially have profound impacts on public health. These reactions decrease
the indoor level of ozone, while simultaneously increasing the levels of these secondary byproducts. This
decrease in indoor ozone levels explains why indoor levels may be considerably less than those outdoors.
But from a public health standpoint, the reduction in indoor ozone signals potentially more toxic
byproducts. Indeed, the secondary byproducts from indoor chemistry resulting from elevated outdoor
ozone levels may be partially responsible for elevated health consequences commonly associated with
outdoor ozone and particulate matter during air pollution episodes (Weschler, 2006). Levin (2008) has
called this situation "the big threat" to public health from climate change.
15This represents 2 percent - 13 percent of the current (2008) NAAQS of 0.075 ppm.
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Recent studies16 indicate that ozone reacts with the constituents of carpet, cleaning products and air
fresheners, paints (particularly the low-VOC paints which use linseed oil), building materials, and a
variety of surfaces, including HVAC surfaces, to produce stable and unstable byproducts. Among the
stable byproducts are compounds that are irritating and toxic. Formaldehyde and other aldehydes, acid
aerosols, and fine and ultrafine particles are among the commonly found secondary byproducts. Of
particular concern is the prolific use of cleaning products and air fresheners, in which selected terpenes
(e.g., a-pinene, limonene, and isopropene) readily react with ozone. Studies suggest that such reactions
produce substantial quantities of these secondary byproducts.
The unstable byproducts, such as the OH radical, can set off a cascade of chemical reactions that,
depending on the indoor and outdoor air constituents, can produce further stable and unstable byproducts.
The potential impact of these reactions on the public health is just beginning to be appreciated (Weschler,
2006).
Indoor Chemistry and Public Health
The adverse health effects of ozone are well known. When inhaled, ozone can damage the lungs.
Relatively small amounts can cause chest pain, coughing, shortness of breath, and throat irritation. Ozone
may also worsen chronic respiratory diseases such as asthma and compromise the body's ability to fight
respiratory infections.17 This is why health authorities advise the public to go inside during days of high
ozone concentrations. But outdoor pollution generally acts as background pollution indoors unless the
outdoor pollutants are captured (e.g., with an air cleaner or filter), adsorbed on indoor surfaces,18 or
transformed through chemical reaction. Since ozone is highly reactive, a number of different reaction
sequences can produce other irritating and reactive byproducts, as well as a number of other chemical
compounds that are harmful to building occupants. Thus, while ozone levels are lower indoors due to
chemical transformations, occupants may be worse off as a result of exposure to secondary byproducts of
ozone's reactivity.
Ventilation Strategies under High Outdoor Ozone Conditions
As described previously, when outdoor pollution levels are temporarily high, it may be advisable to
reduce the outdoor air ventilation rate in order to protect the indoor environment. But if ozone is elevated
outdoors, reducing the outdoor air ventilation rate will not only temporarily reduce indoor ozone levels
but also increase the time for ozone reactive chemistry to take place indoors, potentially increasing the
overall formation of byproducts while decreasing their dilution through ventilation (Weschler, 2001).
Public health could therefore suffer adverse consequences from this strategy. More study of these issues is
needed.
16See for example Weschler (1992,2000,2004,2006,2007), Weschler and Shields (1997, 2004), Nazaroff and
Weschler (2004), Morrison (2008), and Levin (2008).
17See for example EPA's publication Ozone and Your Health available at http://www.epa.gov/airnow/brochure.html.
18Many VOCs are adsorbed on indoor surfaces, particularly fleecy or porous materials. A major problem can occur
when these VOCs are later emitted back into the indoor air as conditions change (e.g. during warm weather).
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The movement toward green buildings has led to increased interest in natural ventilation. In general,
natural ventilation has the potential to save energy and improve the health and comfort of building
occupants. It thus becomes an attractive alternative to mechanical ventilation in response to climate
change. But when outdoor ozone levels are elevated, natural ventilation increases the potential for high
ozone levels indoors and elevated public health risks from indoor chemical reactions. Natural ventilation
strategies will necessarily have to deal with problems of outdoor ozone levels in order to avoid these
public health risks.
Mitigation of Indoor Chemistry Pollution is Feasible
Fortunately, the potentially significant impact of ozone on public health, both from direct exposure to
ozone and from exposure to the byproducts of chemical reactions with ozone indoors, may possibly be
avoided. One important strategy would have manufacturers change their product formulations to reduce
the use of VOCs that readily react with ozone.
Other potential strategies include the use of air-cleaning systems to remove ozone and particles from
ventilation air and from indoor air. However, filters used in HVAC systems may be a cause of concern
when ozone levels are elevated. Filters continually collect dust particles containing VOCs that may react
with ozone to create undesirable byproducts such as formaldehyde that is then delivered into the indoor
spaces. In fact, formaldehyde has been shown to be a common product of reactive chemistry on filters
(Hyttinen et al., 2006). Such phenomena also highlight the need for elevating building maintenance as
part of the climate change strategies to protect public health in buildings.
The synthetic media of the filters themselves also appear to be a problem, as evidenced by analysis of
EPA's data on commercial buildings. From 1994 to 1998 EPA collected comprehensive data on 100
randomly selected office buildings to foster analysis of indoor air quality problems' causes,
consequences, and solutions. Analysis of these data by Lawrence Berkeley National Laboratory showed a
relationship between air filter materials, ozone, and adverse health symptoms of building occupants
(Buchanan et al., 2008). Relative to conditions of low ozone and a fiberglass filter medium, the use of
polyester synthetic filter medium or high outdoor ozone was significantly associated with
fatigue/difficulty concentrating. However, the combination of both high outdoor ozone and
polyester/synthetic filter medium had a significant association with lower and upper respiratory irritation,
cough, eye irritation, fatigue, and headache. These results suggest the possibility that proper filter medium
selection could reduce adverse health symptoms from ozone. Further study is underway.
Charcoal or other chemical sorbents are currently being used to remove ozone within filtration systems,
and the practice is suggested for use in high ozone areas. These systems require careful monitoring and
diligent maintenance, also stressing the need for improvements in maintenance of buildings in the future.
Experiments with the use of ultra-violet photocatalytic oxidation (UVPCO) air-cleaning systems show
promise for removing VOCs from indoor air and offer the opportunity to reduce outdoor air ventilation
rates. These systems use ultra-violet light to promote indoor chemical transformations on the filter media .
Experiments by Lawrence Berkeley National Laboratory demonstrate that such systems have the potential
to significantly reduce VOC concentrations at relatively low cost (Hodgson et al., 2005). However, as
with ozone transformations, incomplete oxidation of VOCs in this system was shown to produce
formaldehyde and acedaldehyde byproducts. It was later shown that adding a scrubber with a
chemisorbent to the system effectively removed the unwanted byproducts and, combined with the VOC
removal rate of the UVPCO system, could potentially afford the opportunity for a 50-percent reduction in
outdoor air ventilation (Hodgson et al., 2007).
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Moisture-Related Impacts on Indoor Environments from Climate Change
Much of the dampness and mold problems in buildings result from inadequate control of moisture flows
from rain, snowfall, or groundwater and inadequate control of humidity and condensation in the occupied
spaces and within the building fabric. Given current building construction methods and level of
maintenance, dampness and mold problems in buildings are already quite significant. Mudarri and Fisk
(2007) report that almost half of U.S. homes have dampness and mold problems of the type that have
been associated with respiratory symptoms. Girman et al. (2002) report that 85 percent of office buildings
have had water damage in the past, while 45 percent report having current leaks.
These problems can have significant health consequences. For example, Fisk et al. (2007) conducted a
meta-analysis of a number of studies concerning the relationship between dampness and mold in homes
and respiratory symptoms. They concluded that damp and mold conditions in homes are associated with
increases in respiratory and asthma-related health outcomes of approximately 30 percent to 50 percent.
That the analysis was limited to studies in homes, in part, reflected the limitations of studies in other
building types for such a meta-analysis. However, Mudarri and Fisk (2007) reviewed available studies in
office buildings and schools and concluded that, while not sufficiently robust to draw definitive
conclusions as was done in homes, the studies tend toward supporting the hypothesis of a strong
association. Mudarri and Fisk (2007) estimate that dampness and mold in homes accounts for
approximately 21 percent of asthma prevalence in the U.S.
Increased relative humidity from climate change will increase the moisture content of materials indoors
and thus increase the risk of mold growth. These conditions will be exacerbated as periodic heavy
rainfalls will likely stress the ability of buildings of all types to adequately manage excess water flow. The
current prevalence of dampness and mold conditions in U.S. buildings already suggests a lack of proper
building defenses against excess moisture flows. In the absence of increased maintenance and retrofit
activity in the U.S. to control moisture, these problems could easily grow exponentially in the face of
increased humidity, heavy rainfall, storms, and flooding. Local flooding along streams and rivers and
flooding along the coastline in the East and Gulf Coast regions from storm surges and sea level rise will
create additional problems. The rampant mold problems caused by flooding during Hurricane Katrina
(Hamilton, 2005) provide ample evidence that mold issues could be a significant problem related to
climate change.
Damage caused by flooding plus the abundance of water available to pests will likely increase
opportunities to harbor them and increase the capacity of buildings to support pest infestations.
(Cockroaches, for example, are primarily attracted to water sources and food debris.) This development
could increase exposure to pest allergens, infectious agents, and to pesticides.
Some products have been shown to decompose in the presence of water, causing both health effects and
the decomposition of building materials (Levin, 2008). For example, the decomposition of plasticizers
commonly used in vinyl flooring and adhesives generates byproducts that may be associated with asthma
(Norback et al., 2000).
Among other consequences of flooding are increased exposure to VOCs and formaldehyde in the
temporary housing provided in flooded areas (DHHS, 2007). These houses have high levels of
formaldehyde and VOCs from surface emissions, and their significantly higher surface-to-volume ratio
increases indoor concentrations.
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Given the variety of potentially serious bio-contaminants and other building pollution problems
associated with heavy rains and flooding, a careful analysis of regional vulnerability to moisture intrusion
into existing buildings, and an analysis of building practices to prevent such intrusions in new
construction, would be worthwhile. In addition, widespread dissemination of guidelines for correcting
dampness and mold problems in buildings, integrated pest management techniques, and revised
specifications for temporary housing could help mitigate moisture-related public health consequences of
climate change in buildings.
Ecological Shifts, Disease Vectors, Pests, and Increased Occupant
Vulnerability to Indoor Environmental Conditions
Changes in the ecological balance brought about by climate change can alter the geographical distribution
and biological cycle of many disease vectors, allowing the establishment of new breeding sites and bursts
of disease carriers, thus posing significant disease risks to people. For example, the 1993 hantavirus
outbreak in the southwestern U.S. resulted from the tenfold increase in the rodent population from May,
1992, to May, 1993, after rodent predators had suffered through six years of drought and the heavy spring
rains that followed resulted in an abundance of rodent food (Epstein, 1995). Similarly, outbreaks of West
Nile virus between 2001 and 2005 are correlated with increasing temperature and rainfall during that
period, leading to the expectation that such outbreaks will accelerate with climate change. Ginnan et al.
(2002) also draw attention to possible outbreaks of diseases such as dengue fever and possibly malaria as
possible consequences of climate change (Hales et al., 2002; Rogers and Randolph, 2000).
There are three important indoor environmental quality issues associated with the spread of
communicable diseases in buildings. All of them relate importantly to building maintenance. The first
highlights the importance of maintaining adequate ventilation control. Lower ventilation rates and the
improper directional control of airflow affects airborne transmission and are associated with higher
disease transmission rates (Li et al., 2005, 2007). This is important in all buildings, but particularly in
hospitals, schools, and other high-occupant-density buildings such as barracks and prisons where
increased respiratory ailments have been associated with decreased ventilation rates (Seppanen et al.,
1999; Brundage et al., 1988; Drinka et al., 1996; Hoge et al., 1994). Related to ventilation is the control of
airflow from contaminated areas (especially in hospitals) that needs to be directed away from uninfected
occupants.
The second environmental quality issue relates to transmission through contact, either direct contact with
infected persons or indirect contact by touching common surfaces such as door knobs, drinking fountains,
phone handles, and computer key boards. Policies that encourage the isolation of infected individuals
(e.g., telecommute when sick), and building maintenance practices (e.g., clean/disinfect common surfaces
regularly) can help limit transmission, as can the avoidance of overcrowded conditions.
Third is the potential for disease vectors (e.g., rodents, insects, arthropods, birds, fungi) to enter and
proliferate in buildings. Reducing the pest-carrying capacity of buildings through proper maintenance
reduces the potential for disease transmission from these vectors. Blocking entry points, minimizing their
dispersal potential, removing access to food and water, minimizing areas of potential harborage, and
similar IPM maintenance activities would reduce disease vectors indoors.
In addition to considering disease-carrying pests, Quarles (2007) provides a useful summary of potential
impacts of climate change on populations of structural pests, crop pests, and forest pests. For example:
Milder and shorter winters could increase the population and geographic distribution of pests
such as ants, flies, wood-boring beetles, and termites.
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Increased population density and range of crop pests could create serious challenges. For
example, increased temperature could extend the range of pink bollworm from Arizona and
Southern California into the Central Valley of California, causing considerable crop damage.
Higher nighttime temperatures will likely accelerate the growth rates of caterpillars such as the
cabbageworm and increase damage from pest nematodes and the diamondback moth.
Warmer winters will increase the survival rate of plant pathogens, and increased plant growth will
likely increase pathogen density.
The mountain pine beetle produces one generation per year compared. The range and extent of
damage has already greatly increased in the Canadian pine forest. This beetle also populates the
Rocky Mountains.
As lower mountain slopes and peaks get warmer, plant, animals, and pests have migrated
upwards, so that insects and insect-borne diseases are now being reported at higher elevations.
Poison ivy is expected to grow more rapidly and with more potent toxin as carbon dioxide levels
increase.
Increased Pesticide Exposure is Likely
An expected response to the proliferation of pests, particularly those that carry diseases that seriously
affect human health or the health of plants and animals important to agriculture, is the increased use of
pesticides and herbicides. In urban areas, for example, eradication programs are used to control pest
infestations (e.g., mosquitoes that carry the West Nile Virus; Gypsy Moths). In agriculture, the spraying
of pesticides is already common. Pesticides sprayed outdoors can find their way indoors through air
exchange or can be brought in on clothing, skin, and especially on shoes. People living close to
agricultural operations may be at particularly high risk. Urban dwellers where pesticides are commonly
used may also be at elevated risk. Children are particularly vulnerable because they play in the dirt and on
the floor (EPA, 1990). Building owners will likely respond to increased infestation (e.g., of rodents, ants,
cockroaches) with the use of pesticides, adding to occupant exposure.
It is not clear what the long-term implications of increased human exposure to pesticides would be
exactly, but it must be considered an important concern. The increased application of IPM techniques,
which minimizes pesticide use in buildings (and in agriculture), would be an important avenue to pursue.
Potential Increased Population Vulnerability to Disease
Climate change is expected to deplete the upper stratospheric ozone layer and thereby increase exposure
to ultraviolet (UV) radiation. This eventuality raises the potential for such exposures to suppress immune
responses to various diseases and to vaccinations (de Gruijl et al., 2003), and it could leave the general
population more vulnerable to disease outbreaks.
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Implications
In general, buildings will be used as shelters to avoid exposure to disease vectors outdoors, to avoid
excessive exposure to UV radiation, and to avoid extreme environmental events such as heat waves. This
fact presents a particular challenge. If indoor environments are to be relied upon to protect the public, a
paramount concern would be whether the indoor environment itself will be able to provide environmental
conditions conducive to supporting the health and well-being of populations made more vulnerable by
disease, UV radiation, and other environmental stressors, particularly in light of the stresses on building
structures and building equipment capacity discussed in this chapter. A systematic review of this issue
should be of primary concern to those planning strategies for adapting to climate change. Design
strategies for new buildings in vulnerable locations, as well as the improved maintenance of existing
buildings would be critical subjects of interest.
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Chapter 4: Public Health Cost of Climate Change Resulting
from Changes in Indoor Environments
Overview
This chapter provides a very rough estimate of the economic value of the public health impacts of climate
change on indoor environments as described in Chapter 3. The estimates are limited to the economic
value of the impacts on public health; they do not account for expenditures or other adaptations that may
occur as society attempts to adjust to such impacts.
Purpose of a Quantitative Economic Assessment
The impact of global warming on the outdoor environment is reasonably robust in qualitative terms, but
quantitative estimates are much more problematic. Similarly, while it is possible to describe in qualitative
terms how climatic changes might affect indoor environmental quality, attempts to quantify those changes
are destined to yield highly uncertain results. Therefore, the assessments provided here are of a very
coarse grain. Their purpose is only to help determine whether the anticipated changes to indoor
environmental quality are likely to be minor or major public health concerns, or somewhere in between,
in order to help policy makers and researchers set priorities for further research and planning.
Methodology
The economic value of changes in public health, comfort, and productivity are estimated in terms of
percentage increments to baseline public health costs of the current inadequacies of indoor environmental
quality. The assessments are made first by establishing baseline public health costs and then by estimating
a likely percentage change from that baseline due to specific climate change effects on the indoor
environment. The total public health cost is estimated by summing the public health cost of specific
climate change effects. Further, the public health costs that are calculated are limited to those solely
related to the cost of public health impacts resulting from changes to indoor environmental quality; they
do not include costs of mitigating or adapting to those changes.
Time Frame
Various government publications on climate change use different time frames to predict environmental
impacts, but generally seem to adopt a perspective of somewhere between 50 years and the end of this
century. This assessment uses the same general time frame.
Discounting
Since public health costs are evaluated overtime, it is appropriate to discount future costs. There are three
time frame issues to consider for this analysis. The first relates to situations in which a given health
impact from exposure is delayed after an initial climate change effect occurs. The second relates to
situations where exposure in the absence of climate change is expected to change overtime. And the third
relates to the fact that climate change itself does not happen all at once, but is expected to evolve.
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Health impacts that are delayed: Most health effects discussed below occur shortly after
climate change alters exposure. The one exception for this analysis is the increase in premature
deaths caused by long-term exposure to environmental tobacco smoke (ETS). Generally,
premature death estimates are based on lifetime exposure, which for the purpose of this analysis
is assumed to be 70 years.
Exposure that is expected to change independent of climate change: The incidence of
smoking is declining in the U.S., so it is assumed that exposure to ETS in the absence of climate
change would gradually decline to 40 percent of its current level over a 25-year period.
Climate change effects evolve over time. Climate change and its impacts are not expected to
occur all at once but rather to evolve over time. For this analysis, a 75-year time frame is used to
account for this effect.
The basic estimates of public health cost are first presented without discounting. Discounted values and
adjustments for the final estimates are then made using discounts rates of 3 percent and 7 percent.
Estimating Baseline Public Health Costs of Current Indoor Environmental
Quality Conditions
Some quantitative relationships between specific indoor environmental conditions and various measures
of health, comfort, and productivity have been reported in the scientific literature. A few studies have also
attempted to evaluate the economic cost of these impacts. Some of these studies, along with independent
analyses, are used here to establish baseline effects of indoor environmental quality on public health and
the associated economic costs. These baseline public health costs represent current conditions, absent any
impact from climate change. It is assumed that baseline conditions in the absence of climate change
would remain constantexcept for exposure to ETS, which is expected to decline. These baseline
impacts serve as the basis for assessing the incremental effects of climate change resulting from increased
indoor exposure to risk factors for health, comfort, and productivity-related effects.
Considerations Related to Environmental Tobacco Smoke and Radon
ETS: As discussed below, recent estimates of the impact of ETS on a variety of health endpoints are
substantial. However, public attitudes toward smoking and ETS exposure have been changing over the
past decade, and smoking is becoming less prevalent. Smoking restrictions in public and commercial
buildings also have served to reduce exposure to ETS. These trends are expected to continue to some
extent. Therefore, it is assumed that the prevalence of smoking will decline in equal decrements over the
next 25 years, from current levels of approximately 25 percent to 10 percent, and remain constant after
that. In other words, it is assumed there will always be some minimum proportion of the population that
smokes (in this case 10 percent) and ETS exposure will decrease in proportion to the decline in smoking.
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Radon: According to current estimates, exposure to radon is responsible for 21,000 premature deaths
each year (EPA, 2003). Radon is a colorless, odorless radioactive soil gas that enters buildings (mostly
homes) through cracks and crevices in the foundation. How much radon enters a building depends on the
radon concentration in the soil, the available paths for entry (e.g., cracks in the foundation), and the
pressure difference between the indoors and the soil beneath the foundation. A negative pressure indoors
relative to the soil will tend to draw radon gas into the building. The main potential impact on radon
exposure from climate change is a reduction in ventilation, which would tend to increase concentrations
of indoor contaminants. However, the impact of ventilation reductions on the pressure difference between
the indoors and the soil are uncertain and could well neutralize or even reverse radon exposure. Therefore,
climate change's impact on radon exposure is assumed to be negligible and is not included in this
analysis.
Baseline Cost Categories
The categories of public health impacts from indoor environmental exposures for which baseline costs are
estimated are exposures to ETS, heat waves, and exposures resulting in public health impacts related to
sick building syndrome, allergies and asthma, and communicable respiratory illnesses. These are
discussed below.
Baseline Public Health Costs from ETS Exposure
Baseline Rates of Mortality from ETS Exposure
In 1992, EPA published its risk assessment of ETS and declared it to be a class A human carcinogen
responsible for approximately 3,000 deaths from lung cancer each year, and 150,000 to 300,000 lower
respiratory tract infections (LRI) in infants and children under 18 months of age, resulting in 7,500 to
15,000 hospitalizations (EPA, 1992). The report did not cover the effects of ETS exposure on heart
disease.
In 2005, the California Air Resources Board (CARB) provided updated information on the impacts of
ETS exposure and health for California and the U.S. (CARB, 2005). The report included estimates of the
effects of ETS exposure on heart disease and other impacts on children. It leaves the EPA estimate for
LRI unchanged, updates the cancer impact to 3,400 deaths a year, and adds 46,000 (22,700 - 69,600)
deaths from ischemic heart disease, 430 deaths from sudden infant death syndrome (SIDS), and 202,300
excess asthma episodes each year. These and other impacts reported by CARB are presented Tables 4-la
and 4-lb.
Table 4-la: Attributable Chronic Mortality Effects Associated with ETS Exposure
Cardiac death
(Ischemic heart disease deaths)
46,000
(range: 22,700 - 69,600)
Updated 2005
Lung cancer death
3,400
Updated 2005
SIDS
430
Updated 2005
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Baseline Public Health Cost of Mortality from ETS Exposure
Economic valuation of increases or decreases in the risk of death associated with some activity are
customarily based on the "value of a statistical life" (VSL). The VSL is derived from the value that the
market places on a unit risk of death. The range of values from a number of meta-analyses is $1 million to
$10 million per statistical death. The Office of Management and Budget recommends a default value of
$5 million, although most agencies tend to use higher values.19 EPA, for example, uses $7.4 million as a
default value, although some EPA offices may use higher or lower values.20 This analysis uses the EPA
value of $7.4 million per statistical life.
Using updated figures from CARB (2005), premature deaths each year from cancer, heart disease, and
SIDS associated with ETS exposure total 49,830, which when valued at $7.4 million each comes to
$368.7 billion. By the end of the century, however, this amount would be reduced to 40 percent of that
level, $147.5 billion, to account for the estimated decline in smoking.
liasclinc Annual Mortality Costs from K IS Kxposuiv: S36() hill ion (current) / SI4S hi I li oil (I'ntiiro).
Baseline Public Health Cost of Morbidity from ETS Exposure
The chronic and acute morbidity effects of ETS exposure estimated by CARB (2005) are provided in
Table 4-lb.
Table 4-lb: Attributable Chronic & Acute Morbidity Effects Associated w/ ETS Exposure
Outcome
Annual Excess #
Comment
Pregnancy
Low birth weight
Pre-term delivery
24,500
71,900
Updated 2005
Updated 2005
Asthma (in children)
# Episodes
# New cases
# Exacerbations
202,300
8000 - 26,000
400,000- 1,000,000
Updated 2005
Conclusion in 1997
Conclusion in 1997
Lower respiratory illness
150,000-300,000
Conclusion in 1997
Otitis media visits
790,000
Updated 2005
19See, for example, Department of Transportation Memorandum RE: Treatment of the Economic Value of a
Statistical Life in Departmental Analyses, (http://ostoxweb.dot.gov/policv/reports/080205.html accessed 5/26/2009.
20See US EPA. Frequently Asked Questions on Mortality Risk Valuation.
(http://vosemite.epa.gOv/ee/epa/eed.nsf/pages/Mortalitv%20Risk%20Valuation.html#WhvDoesEPAPlaceVSL
National Center for Environmental Economics. Accessed 5/26/2009.
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EPA has estimated unit costs for some acute and chronic symptoms of illness. Of significance for this
analysis is the estimated lifetime unit cost of approximately $145,000 for low birth weight (EPA, 2002)
and approximately $41,000 for chronic asthma (new cases of asthma) (EPA, 1999), in 2008 dollars. Using
these figures and ignoring the acute health effects identified above, the baseline annual cost of low birth
weight is approximately $3.6 billion. Using the midpoint of 17,000 excess new cases of asthma, the
annual baseline cost is approximately $0.7 billion, for a total of approximately $4.3 billion in 2008
dollars. Adjusting this for reduced smoking prevalence yields a baseline cost of $ 1.7 billion.
Baseline Morbidity Cost from ETS Exposure : $4 billion (current) ($2008) / $2 billion (future) ($2008)
Baseline Public Health Costs of Heat Waves
A large number of health effects are related to extreme heat. This analysis focuses on the number of heat-
related deaths. Unfortunately, there is a great deal of uncertainty on the overall number of deaths from
extreme heat events. For example, EPA (2006) suggests that an examination of multiple extreme heat
events in different regions indicates that extreme heat events result in approximately 1,700 - 1,800 excess
deaths per summer, roughly an order of magnitude greater than the national annual average of 182. On
the other hand, using death certificates on which the causes of death is recorded, the Centers for Disease
Control and Prevention (CDC) estimates that 3,442 deaths between 1999 and 2003 (annual mean of 688
deaths) resulted from exposure to extreme heat, including deaths where hypothermia was recorded as a
contributing factor. Using the more conservative CDC estimate of 688 deaths annually from extreme heat
events, and $7.4 million value for a statistical life, the baseline public health cost of premature deaths
from heat waves each year is estimated to be $5.1 billion.
Baseline Mortality Cost from Heat Waves: $5 billion
Baseline Public Health Cost of Sick Building Syndrome, Heat Waves, Allergies
and Asthma, and Communicable Respiratory Illness
Fisk (2000) estimated the economic value of health and productivity gains that could be attained by taking
actions in buildings to prevent and mitigate poor indoor environmental quality. The study covered issues
associated with communicable respiratory illness, allergies and asthma, and sick building syndrome.
Ideally, the true economic cost of these health impacts would use a market-based value of what people are
willing to pay to avoid having an illness, or the amount that would make people indifferent as to whether
they did or did not have an illness. These values are much less readily available for acute illnesses.
Therefore, the health care costs (direct costs) of such illnesses plus work time (or productivity) losses
(indirect costs) are often used. The direct and indirect costing methods, however, can grossly undervalue
the true economic costs, especially for severe illnesses, because they imply that society has no interest in
preventing such illnesses other than saving the productivity and health care resources involved.
The cost estimates in Fisk (2000) used the direct and indirect costing methodology for illnesses, and, in
this way, may be considered conservative. In addition, the study estimated costs of the direct impact of
building factors on human performance (productivity) independent of illness, but many of these direct
impacts are related to lighting, which is not likely to be affected by climate change. Therefore, these
direct productivity impacts are not included here.
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The purpose of the Fisk (2000) study was to determine the public health impact reductions and economic
savings that could be attained if preventive and mitigation actions were taken. The discussion below
draws from that analysis the health and productivity costs associated with current indoor environmental
quality conditions that were used in the current analysis.
Sick Building Syndrome
Sick building syndrome, or SBS, is a constellation of cold or flu-like symptoms experienced by building
occupants that improve when they leave the building. These symptoms include irritation of the eyes, nose,
and skin; headache; fatigue; and difficulty breathing. Approximately 23 percent of office workers
regularly experience at least two such symptoms. Various SBS symptoms are statistically associated with
a number of building factors, such as the type of ventilation system, outdoor air ventilation rates,
chemical and biological contaminants, and particles on surfaces. Associations of SBS symptoms with low
ventilation rates are particularly common.
The main economic impact of SBS is the reduced productivity of those affected. Given the prevalence of
SBS, even a small reduction in productivity could represent a substantial economic burden. EPA
estimated productivity losses from office workers due to SBS were 3 percent, or $60 billion in 1989
dollars, (EPA, 1989), approximately $104 billion in 2008 dollars. Fisk (2000) more conservatively
estimated these losses at 2 percenter $60 billion in 1996 dollars, approximately $82 billion in 2008
dollars. This estimate is conservative in that it does not include losses in non-office environments.
Baseline Public Health Cost: $93 billion ($82 billion - $104 billion) annually ($2008)
Allergies and Asthma
Fisk (2000) estimated that 16 percent to 50 percent of allergies and asthma cases are associated with
building-related risk factors such as moisture problems and bio-contamination, irritating chemicals such
as ETS, and exposure to pets, pest allergens, and pollen. This accounts for approximately $2 billion to $8
billion annually in medical cost and lost ore severely restricted work days. In a related study, Mudarri
and Fisk (2007) estimated that exposure to dampness and mold in homes accounts for approximately 4.6
million cases of asthma at an annual cost of approximately $3.5 billion, which falls within the Fisk (2000)
estimate.
Baseline Cost: $5 billion ($2 billion to $8 billion) annually ($2000) / $6 billion (2008)
Communicable Respiratory Illness
Fisk (2000) estimated that 9 percent to 20 percent of respiratory illnesses are associated with building-
related factors such as ventilation, air cleaning, air re-circulation, and crowding. This translates to
approximately $6 billion to $14 billion in annual costs: $3billion to $7 billion in health care costs, plus $3
billion to $7 billion in lost work or severely restricted work days. Between 16 million and 37 million
cases of the common cold and influenza are estimated to be associated with building-related indoor
environmental factors. However, communicable disease outbreaks can be more serious than is indicated
here because of the potential premature mortality of vulnerable populations. Because premature death
may be a serious climate change issue, the baseline cost in this category is thought to be greatly
underestimated.
54
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Baseline Cost:$10 billion ($6 billion - $14 billion) annually ($2000) / $13 billion (2008)
Table 4-2 summarizes the baseline annual cost estimates associated with poor indoor environmental
quality.
Table 4-2: Baseline economic cost of health, comfort, and productivity impacts
Health or Exposure
Category
Approximate
Annual Cost
(Billions)
Comment
ETS exposure mortality
$369 (current)
$148* (future)
49,830 premature deaths from cancer, heart disease,
and SIDS (from CARB, 2005)
ETS exposure morbidity
$4 (current)
$2* (future)
Includes 24,500 cases of low birth weight and 17,000
new cases of asthma only (CARB, 2005)
Heat waves
$5
688 premature heat-related deaths including
hypothermia as a contributing factor (CDC, 2006)
SBS
$93
Midpoint of productivity loss of $73 billion from SBS
(Fisk, 2000) and $87 billion (EPA, 1989), adjusted for
inflation to 2008 dollars
Allergies and asthma
$6
Midpoint of $2 billion - $8 billion (Fisk, 2000),
adjusted for inflation to 2008 dollars
Communicable respiratory
illnesses
$13
Midpoint of $6 billion - $14 billion (Fisk, 2000),
adjusted for inflation to 2008 dollars
Total Baseline Annual
Cost
$490 billion (current)
$267 billion (future)
* Adjusted to 40 percent of the dollar value to account for declining smoking prevalence.
Public Health Cost Impact Categories
Consolidated Cost Impact Categories
The baseline costs in Table 4-2 are consolidated below under public health cost impact categories useful
for this analysis. The cost impact categories, and what they include, are summarized in Table 4-3. Since
only the economic value of health effects resulting from indoor environmental changes is being evaluated,
the cost impact categories describe the health effects being estimated.
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Table 4-3: Consolidated Cost Impact Categories
Category
Source
(1) Sick building syndrome (SBS)
Increased indoor temperatures and pollution from
VOCs, pesticides, and formaldehyde
(2) Heat waves
Extreme heat events
(3) Allergies, asthma, and respiratory symptoms
Moisture-related contaminants such as mold, dust
mites, cockroaches, and rodents, plus symptoms from
fine particles resulting from indoor air chemistry
involving ozone
(4) Communicable diseases
Ecological shifts that increase disease vectors and
from reduced immunity due to ultraviolet radiation
(5) All health effects except heat waves
Reduced ventilation, which increases all indoor air
contaminants. Includes all the effects in Table 4-2
except heat waves
Level of Impact
Given the great uncertainty in quantifying public health effects and cost impacts, only a very rough
estimating procedure was attempted. For each cost impact category, reasoned judgments were used to
assign a percentage change impact, as follows:
Low-level impact (1 percent - 20 percent)
Medium-level impact (21 percent - 35 percent)
High-level impact (36 percent - 50 percent)
For heat waves, however, a specific estimate available in the literature was used. The economic value of
each cost impact category was then summed to estimate the total cost.
Despite their imprecision, these assessments may be useful for suggesting where major public health costs
are likely to be. The assessments also may help policy makers determine whether the climate change
impacts on indoor environmental quality are of major or minor concern compared to other types of public
health impacts.
The rationale for the individual estimates is described more fully below. No attempt was made to estimate
the economic expenditures likely to occur as the public adjusts to indoor environmental changes (e.g., the
cost of increased air conditioning systems to cool buildings, mold remediation expenses, etc.), though
preventing those costs or reducing them through research and recommendations of the most cost-effective
alternatives would be worthwhile.
The climatic changes and associated indoor environmental and health-related effects discussed in
Chapters 2 and 3 are summarized in Table 4-4, along with the applicable cost impact category.
Quantitative estimates of the level of impact and the associated economic costs of the public health,
comfort, and productivity losses follow.
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Table 4-4: Effects of Climate Change (Global Warming) on Indoor Air Quality
Climatological Effect
and Adaptations
Indoor Environmental Effect
Effect on indoor
climate and indoor
pollution
Effect on health,
comfort &
productivity
Value (cost) of health,
comfort, & productivity
change*
Outdoor Temperature
Mean rise in outdoor
temperature rise
Indoor temperature
rises.
Sick Building
Syndrome (SBS)
increases from
temperature rise.
Percentage increase in
SBS (1)
Increased use of air
conditioning
Potential for increased
off-gassing of VOCs.
Potential increase in
respiratory
symptoms
Percentage increase in
SBS (1)
Increased frequency and
intensity of heat waves
Inability of air
conditioning to
condition indoor air
Extreme heat stress
Multiple effects
Percentage increase in
respiratory symptoms (2)
Percentage increase in
premature death (2)
Outdoor Pollution
Increased outdoor
pollution (especially
particulates and ozone)
Increased particulates
and ozone come indoors
Increased ozone reaction
byproducts (indoor
chemistry)
Increased
respiratory ailments
Increased SBS and
respiratory
symptoms
Percentage increase in
respiratory symptoms (3).
Percentage increase in
SBS (1)
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Climatological Effect
and Adaptations
Indoor Environmental Effect
Effect on indoor
climate and indoor
pollution
Effect on health,
comfort &
productivity
Value (cost) of health,
comfort, & productivity
change*
Moisture and Water
Events
Increased mean outdoor
humidity
Temporary housing
provided in flooded
areas
Increased indoor relative
humidity, condensation,
and mold growth
Increased frequency and
intensity of extreme
precipitation episodes,
with flooding in inland
areas
Higher intensity of
storm surges and sea
level rise in coastal
areas, with increased
flooding in East and
Gulf Coast Regions
Increased harborage of
rodents
Increased wet, damp
conditions, building
damage, and mold
Increased rodent
infestation indoors due
to rodent migration from
outdoors to indoors and
possible cockroach
infestation due to
dampness
Increased use and
exposure to pesticides
Increased formaldehyde
and VOC exposures
Asthma, allergies,
and respiratory
symptoms
Asthma, allergies,
and respiratory
symptoms.
Allergies, asthma,
and respiratory
symptoms.
SBS from
pesticides,
formaldehyde, and
VOC
Percentage increase in
allergies, asthma, and
respiratory symptoms (3)
Percentage increase in
allergies, asthma, and
respiratory symptoms (3)
Percentage increase in
allergies, asthma, and
respiratory symptoms (3)
Percentage increase in
SBS (1)
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Climatological Effect
and Adaptations
Indoor Environmental Effect
Effect on indoor
climate and indoor
pollution
Effect on health,
comfort &
productivity
Value (cost) of health,
comfort, & productivity
change*
Outdoor Air Ventilation
Pressure to reduce
energy use to lower
GHG; because of the
cost of increased air
conditioning results in
reduced outdoor air
ventilation
All existing indoor
pollutants rise in inverse
proportion to reduced
ventilation
Increases in all
existing indoor air
health, comfort, and
productivity effects
Percentage increases in
all categories except heat
waves (5)
Ecological Shifts and
UV Radiation
Changes in population
and geographical
distribution of disease
pathogens, vectors, and
hosts
Increases in disease
outbreaks
Disease
transmission in
indoor environments
Percentage increase in
communicable diseases
(4)
*The numbers in parentheses correspond to the cost impact category in Table 4-3
Estimates of Public Health Costs from Climate Change Impact on Indoor
21
En vironments
(1) Estimated Increase in Public Health Cost from Sick Building Syndrome (SBS)
Estimated SBS increase from increased indoor temperature: Higher temperatures have been
associated with poorer perceptions of IAQ (Bergland and Cain, 1989; Fang et al., 1998) and with higher
rates of unsolicited occupant complaints (Federspiel, 1998). Temperature and perceived IAQ are also
associated with SBS and productivity (Seppanen and Fisk, 2005). In addition, there is evidence of
increased respiratory effects resulting from higher temperatures. This was the predominant effect
measured in a study of the impact of particles on workers (Mendell et al., 2002). In addition to higher
temperatures, higher levels of SBS have been associated with air-conditioned buildings (Seppanen and
Fisk, 2002).
21Numbers in parentheses below correspond to the numbers in Tables 4-3 and 4-4.
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It is not clear how pervasive these effects will be because air conditioning will lower indoor temperatures
and mitigate the temperature effect, while the use of air conditioning will itself contribute to increasing
adverse health effects. Further, the impact of air conditioning has only been shown when comparing
buildings with and without air conditioning, not buildings with different levels of air conditioning use.
For the purpose of this analysis, and for simplicity, only SBS affects are considered. Further, because of
the counteracting effects (air conditioning lowers temperature) and the uncertainty about the air
conditioning effect, the impact of rising temperature and the increased use of air conditioning is not
expected to be large.
Estimated SBS increase from increased outdoor pollution: Higher outdoor temperatures enables the
air to absorb more moisture, leading to a longer time to saturation and, thus, less frequent light rainfalls
resulting in an increase in drought and forest fires. The forest fires will increase outdoor pollution. In
addition, an increase in temperature will increase the chemical reaction of ozone primary and precursor
pollutants from motor vehicles and industrial emissions such as VOCs and oxides of nitrogen (NOx) to
produce increased levels of ozone. This increase in outdoor pollution will increase ozone and particulates
indoors, and it will also likely cause people to spend more time indoors22.
Higher indoor ozone levels will create reactive byproducts, such as fine and ultrafine particles,
formaldehyde, acetaldehyde, acetone, glycolaldehyde, formic acid, and acetic acid, particularly in the
presence of terpenes which are common in cleaning products (Weschler, 2006, 2006a; 2007, 2007a;
Nazaroff and Weschler, 2004; Levin, 2008). Reactive byproducts, along with outdoor pollutants entering
the indoors, contribute to increased SBS.
EPA (2009) estimates that the increase in summertime average Maximum Daily 8-hour Average (MDA8)
ozone concentrations across all the modeling studies tends to fall in the range of 2 - 8 parts per billion
(ppb), which represents about a 2 percent to 13 percent increase. However, peak levels are expected to
rise considerably and could be a matter of serious concern. Taken together, the impact on SBS indoors
from increases in the average and peak ozone level rise outdoors is assumed to fall in the middle of the
low impact category.
Estimated SBS increase from the use of temporary housing: Earth's rising temperature along with an
increase in the frequency and intensity of extreme precipitation events and flooding, is expected to
continue. As temperatures rise, thermal expansion of the oceans and melting glaciers contribute to the
intensity of precipitation events, sea level rise, and thus the flooding of streams, rivers, and coastal areas
that will create the need for temporary housing. Temporary houses have high levels of VOCs from
surface emissions and their significantly higher surface-to-volume ratio, which increases indoor
concentrations. Flooding is also expected to increase the harborage of pests and the use of pesticides. An
important consequence of flooding, therefore, is the increased exposure to VOCs and formaldehyde of
persons in temporary housing, which is assumed to increase the prevalence of SBS symptoms.
Because flooding and the use of temporary housing is mostly limited to flooded areas, on average this
impact is considered to be in the low end of the low impact category.
Overall economic cost of increased SBS: Given the analysis above, the percentage increase in SBS is
assumed to fall within the low-level impact category of 1 percent - 20 percent.
liaseline annual costs ol'SliS = S()3 hi 11 i oil (Table 4-2).
A Ion-level impact
-------
Estimated annual cost impact = approximately $1 billion - $19 billion.
(2) Estimated Increase in Public Health Costs from Heat Waves
Estimated increase in morbidity from heat waves. Increased morbidity from heat waves includes heat
cramps; heat exhaustion with symptoms such as intense sweating, thirst, fatigue, fainting, nausea, and
headache; and heatstroke, a severe illness that can lead to serious long-term impairment. While these are
important health impacts, data on their public health cost are not readily available. They are therefore not
included in this analysis.
Estimated increase in mortality from heat waves: Ebi and Meehl (2007) report on a study (Hayhoe et
al., 2004) that assumes a linear increase in heat-related mortality with increase in temperature. The study
estimates, a 2-to-7-fold increase in heat-related mortality in California. This is consistent with reports
from research at King's College London, where it is suggested that the increase in heat-related deaths in
London from climate change may reach four times the current level23. Ebi and Meehl (2007) project only
a 70-percent increase in extreme heat days by the end of the 21st century and argue that projections of
extreme heat conditions are not sufficient to predict increases in morbidity and mortality. In addition to
extreme heat conditions, other factors such as the changing characteristics of the population, the ability to
acclimatize to high temperatures, and adaptation strategies that may be implemented are also important
(Ebi and Meehl, 2007).
For the purposes of this analysis, a simple linear relationship between the number of extreme heat days
and heat-related mortality is assumed. The 70-percent increase in extreme heat days would therefore
translate to a 70-percent increase in the baseline cost. To be consistent with providing a range of impacts,
an assumption of + 10 percent was used, yielding an increase of 60 percent - 80 percent.
Baseline annual public health costs of heat-related mortality = $5 billion
A 60-percent to 80-percent increase assumed
Estimated annual cost impact from heat waves = approximately $3 billion - $4 billion
(3) Estimated Increase in Public Health Cost from Allergies, Asthma, and Respiratory
Symptoms
Estimated increase from humidity, dampness, and mold: Damp conditions caused by increased indoor
humidity and condensation, along with heavy rainfall and flooding due to climate change, create an
optimum environment for mold growth, which contaminates indoor environments. As described
previously, dampness and mold are associated with asthma and asthma-like respiratory symptoms.
However, condensation and dampness are functions of relative humidity (RH), not just absolute humidity.
It was previously noted that with climate change, indoor temperatures are likely to rise along with outdoor
temperatures. This rise in indoor temperatures will, to some extent, counter the rise in absolute humidity
and tend to mitigate against the rise in RH. Thus, the impact of increased humidity is assumed to be
relatively minor.
23See news article from Mail; Online, Jan 25, 2010. Science and Tech. Heatwave Deaths will Quadruple in Cities
like London, say Climate Experts, http://www.dailvmail.co.uk/sciencetecli/article-1160959 . Accessed on 1/24/2010.
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On the other hand, the increase in heavy rains and flooding previously described will be accompanied by
dampness and mold that will last long after the heavy rain and flood conditions have passed. Areas where
dampness and mold are already present are likely to experience a substantial increase in those problems,
while some areas where mold is not currently a problem will begin to experience problems for the first
time. Because electric power outages frequently accompany heavy rains and flooding, efforts to pump
water out of buildings or use air conditioners or dehumidiflers to assist in drying can be greatly impeded,
and this development will extend the likely time of mold growth and exposure well beyond the flooding
or heavy rain events. Further, once it infests a building, mold can be a chronic and continuous problem
unless thoroughly mitigated. Mold within walls and framing elements is often extremely difficult or
expensive to remove. Thus, this impact is assumed to be in the medium impact category.
Estimated increase from pest infestations: Damage caused by flooding plus the abundance of water
available to pests, along with other ecological shifts previously described, will likely increase pest
harborage opportunities, and building damage caused by heavy rains and flooding may be expected to
increase the carrying capacity of buildings for pests. This will likely increase exposure to pest allergens.
Once it occurs, an infestation can last for a long period. However, unlike communicable diseases where
an initial increase can be multiplied several fold as the disease spreads, the impact of allergens is likely to
be limited to the proportional increased infestation. This impact, therefore, is assumed to be in the low
impact category.
Total estimated public health cost from allergies, mold, and respiratory symptoms: Overall, it is
assumed that mold infestations will dominate the impacts on allergies, asthma, and respiratory conditions
which are in the medium impact category, and the contribution of pest infestation and humidity will not
be sufficient to raise that level. The overall impact, therefore, is assumed to remain in the medium impact
category.
Baseline annual costs of allergies, asthma & respiratory symptoms = $6 billion (Table 4-2).
A medium-level impact assumption (21 percent - 35 percent) used
Estimated annual cost impact from allergies, asthma, and respiratory symptoms = approximately
$1 billion - $2 billion
Estimated Increase in Public Health Cost from Communicable Diseases
As previously described, alterations in the ecological balance brought about by climate change will vary
the geographical distribution and biological cycle of many disease vectors, allowing the establishment of
new breeding sites and bursts of disease carriers, thus posing significant disease risks to humans.
Episodes such as the hantavirus outbreak in the southwestern U.S. in 1993 and the West Nile virus
outbreak between 2001 and 2005 are expected to accelerate with climate change.
The fact that communicable diseases have the potential to spread throughout the population increases the
potential impact of this problem, which could easily multiply several fold from current conditions. There
also is some concern that increased exposure to UV radiation due to climate change could make the
population more vulnerable to infection.
Since people spend the vast majority of their time indoors, the degree to which indoor environments are
maintained (e.g., adequate ventilation, cleaning contact surfaces) can reduce the potential for disease
transmission. Maintenance in hospitals, schools, and high-occupant-density buildings is particularly
important. The behavior of occupants (e.g., frequent hand washing, staying home if sick) is also a critical
variable. These issues were addressed in previous chapters.
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Assuming that building O&M practices remain the same as they are today, the impact of climate change
on communicable diseases could be quite large (i.e., medium- to high-level impact). However, a major
portion of building operation practices is ventilation, which is expected to decrease thus raising the
potential for disease transmission. Since the impact of reduced ventilation is estimated separately (see
below), the impact of climate change on communicable diseases is assumed to be in the medium impact
category.
Baseline annual cost for communicable disease = approximately $13 billion
A medium impact assumption (21 percent - 35 percent) used
Estimated annual cost impact for communicable diseases24 = approximately $3 billion - $5 billion.
(5) Estimated Economic Cost for All Health Effects Due to a Reduction In Outdoor Air
Ventilation
The Earth's rising temperature will increase use of air conditioning, which in turn will increase the
amount of greenhouse gases pumped into the atmosphere from burning fossil fuels to generate electricity
to power air conditioners, further perpetuating the temperature rise. To reduce the anthropogenic effect on
the Earth's climate, a number of policies will likely be put in place to reduce energy use and, therefore,
reduce greenhouse gas emissions. Among the likely actions to be taken to reduce greenhouse gas
emissions and energy use are tightening building envelopes and reducing mechanically driven outdoor air
ventilation to maintain indoor air temperatures. Since outdoor air ventilation is used to "dilute" indoor
contaminants, its reduction will cause an increase in indoor exposures to airborne contaminants generated
indoors. Thus, with the exception of heatwaves, all the baseline economic costs associated with health,
comfort, and productivity as previously described are expected to increase as a result of reduced
ventilation.
Indoor concentrations of pollutants that are generated indoors are roughly inversely proportional to
outdoor air ventilation rates, and indoor concentrations of pollutants generated outdoors are directly
proportional. Thus, reductions in outdoor ventilation rates would increase indoor concentrations of
pollutants generated indoors and temporarily reduce the indoor levels of pollutants generated outdoors.25
During the energy crisis of the 1970s, ventilation standards were effectively reduced from 15 to 5 cubic
feet per minute (cfm) per occupant, a 66-percent reduction. Were a similar scenario to occur, it would
constitute a high-level impact. Most commercial buildings, schools, and multistory apartment buildings
are mechanically ventilated, so reduced ventilation can easily be achieved through operational changes.
However, single-family residences rely almost exclusively on natural ventilation. The most significant
ventilation reductions in single-family homes would be achieved by increasing insulation, replacing
windows, or performing other retrofits that likely would occur over many years. Since people spend more
time at home than in other buildings, the overall reduction in ventilation is tempered by the difficulty of
doing so in homes. A medium impact rather than a high impact assumption for ventilation reduction is
therefore used.
24Because the baseline cost of this category does not include mortality estimates, this is likely to be a gross
underestimation of this impact.
25The decrease in exposures to outdoor pollutants is true in the short run; however, the tendency for outdoor
pollutant levels to also be achieved indoors as background levels (steady state condition) would remain.
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Since these cost impacts represent conditions that would occur after 75 years, or toward the end of the
century, all the ETS-related ventilation impacts are adjusted to reflect the decrease in smoking prevalence
to 40 percent of its current value.
Baseline Annual Economic Cost of All Health Effects from Reduced Ventilation
ETS mortality = approximately $148 billion
ETS morbidity = approximately $2 billion
All other = approximately $112 billion
A medium impact ventilation reduction assumption (21 percent - 35 percent) is used.
Corresponding increase in pollutant concentration becomes 27 percent - 54 percent26
Estimated Annual Cost Impact
Ventilation ETS mortality = approximately $40 billion - $80 billion
Ventilation ETS morbidity = approximately $1 billion - $1 billion
Ventilation Other* = approximately $30 billion - $60 billion
Total Public Health Cost from Climate Change Impact on Indoor Environmental Quality
Undiscounted and Unadjusted Costs
Table 4-5 presents the total undiscounted and unadjusted costs of climate change's effects on indoor
environmental quality
26Indoor concentrations are inversely proportional to the ventilation rate. The generic equation is C = S/V. where C
is the concentration, S is the emission rate indoors, and V is the ventilation rate. Thus, if V is decreased by x %, i.e.,
Vi = (l-x%)V0, then Ci becomes C0 (l/(l-x%)). Accordingly, assuming that ventilation rate is reduced by 21% -
35% (i.e. x = 21% - 35%), then C is increased by 27% - 54%.
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Table 4-5: Undiscounted Public Health Cost Impact Estimates
Category
Annual Public Health Cost (billionS)
Low
High
Sick Building Syndrome
1
19
Heat Wave Mortality
3
4
Allergy, Asthma, and Respiratory
1
2
Communicable Disease
3
5
Ventilation ETS (mortality)
40
80
Ventilation (morbidity)
1
1
Ventilation (other)
30
60
Total
79
171
Approximate Range
75 - 175
It is thus concluded that the total undiscounted public health cost of climate change impacts on indoor
environments are potentially between the high tens of billions of dollars up to perhaps two hundred
billion dollars per year, with the largest impact coming from reduced ventilation rates. This estimate
represents the annual cost burden that will eventually be experienced toward the end of the century,
valued in current dollars.
Discounted Costs
A change in climate is not expected to occur all at once, but rather will evolve over time. For this
analysis, it is assumed that the full impact estimated above will occur in equal annual increments over a
75-year time frame. This assumption applies to all the health effects estimated.
When estimating costs that occur over a time period, it is appropriate to discount future cost streams.
Future costs are thus discounted using discount rates of 3 percent and 7 percent to achieve a present value,
which is then converted to an "annual equivalent" cost.
When estimating the future cost stream of premature deaths from ETS exposure, two additional factors
are assumed to alter the future cost stream. The annual estimates of premature death from ETS exposures
provided in Table 4-la represent calculations of a steady state population exposure based on mortality
risks from individual lifetime exposures of 70 years. Therefore, when an incremental change occurs in
the population exposure due to climate change, a new steady state condition will ultimately result in a
different annual rate of premature death, and this new rate is assumed to evolve in equal increments over
the assumed lifetime of 70 years.
In addition, as previously described, the current baseline population exposure which is assumed to result
from smoking prevalence of approximately 25 percent is not expected to remain constant, given current
trends away from smoking. For this analysis, it is assumed that smoking prevalence will gradually
diminish in equal decrements to 10 percent in 25 years and remain constant thereafter. Since this
reduction will take place over time, its effect on the future cost stream of premature deaths from ETS
exposure is also incorporated into the discounting procedure.
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Table 4-6 provides the discounting factors when using a social discount rate of 3 percent or 7 percent. The
public health cost calculations presented in Table 4-5, multiplied by the appropriate "annual equivalent"
factors in Table 4-6, represent the discounted public health cost. The discounted public health cost of
climate change impacts on indoor environments is presented in Table 4-7 using discount rates of 3 percent
and 7 percent. It is generally thought that a 3 percent rate is most appropriate for long-term analyses of
societal impacts.
Table 4-6: Discount Factors for Annual Equivalent Impact Estimates
3%
7%
Annual
Equivalent
Annual
Equivalent
Delayed premature death (70 yrs)
0.425
0.216
Incremental climate change (75 yrs)
0.405
0.202
Smoking prevalence reduction from 25 percent to 10
percent in 25 yrs
0.568
0.701
All effects combined
0.115
0.038
Table 4-7: Discounted and Adjusted Annual Equivalent Public Health Cost of Climate
Change on Indoor Environmental Quality (Sbillion)
3%
7%
Low
High
Low
High
Sick Building Syndrome
0
8
0
4
Heat Wave mortality
1
2
1
1
Allergies, asthma, respiratory disease
1
1
0
0
Communicable respiratory disease
1
2
1
1
Ventilation ETS mortality
11
23
4
8
Ventilation ETS morbidity
0
0
0
0
Ventilation other*
12
24
6
12
Total
27
60
12
26
Approximate Range
10-60
*Excludes heat waves
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The rough estimates presented here suggest that the public health cost impact of climate change on indoor
environmental quality would be in the range of $10 billion - $60 billion per year. This range represents
the current value of a varying future stream of annual costs that would occur into the indefinite future,
converted to an annual equivalent. The cost estimates take into account the gradual nature of changes in
climate over time, the delay of onset of mortality from ETS exposure, and the declining prevalence of
smoking in American society. Given the uncertainties and the rough nature of these estimates, it is
perhaps more appropriate to conclude that the discounted and adjusted public health costs are in the low-
to-mid tens of billions of dollars per year, but could be in the high tens of billion of dollars per year if all
health impacts were included.
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Chapter 5: Summary and Conclusions
Overview
This chapter summarizes the major findings and arguments presented in this report and discusses the
implications for public and private actions to protect the public health through improved indoor
environmental planning and control.
Warmer Temperatures
Warmer outdoor temperatures caused by climate change are expected to increase indoor
temperatures.
While partly mitigated by increased use of air conditioning, overall, the rise in indoor
temperatures can be expected to have some health impact, including perceptions of poorer indoor
air quality, increased SBS symptoms, and some increase in respiratory symptoms. Greater use of
air conditioning will likely increase carbon emissions, which in turn will accelerate the warming
effect.
Temperature extremes are expected to experience proportionally higher increases than mean
temperatures, and extreme temperature events will occur more often. This will greatly increase
peak electricity demand, perhaps beyond the capacity to meet the increased demand for air
conditioning, and this will exacerbate the health effects from indoor exposure.
Heat waves will result in a host of health effects, including increased deaths of vulnerable
populations from indoor heat exposures.
Implications
Significant unmet needs for cooling through air conditioning will require greater attention to
alternative cooling strategies in building design (e.g., building orientation, roofing and window
systems) and operational practices (e.g., night cooling). This is consistent with the "green
building" movement, which may be further encouraged in response to climate change.
The generally agreed upon recommended public health response to heat waves is a notification
and response program. This approach does not address the likelihood that many buildings,
including many that are relied upon in these programs to be available to cool sensitive
populations, may not be capable of doing so due to disruptions in energy supplies and building
damages from other climate change events. Further consideration of this issue is needed.
Reduced Outdoor Air Ventilation
Non-industrial buildings account for almost 40 percent of the energy consumed in the United
States. The rise in energy demand for air conditioning combined with the need to reduce carbon
emissions is expected to result in reduced outdoor air ventilation of buildings. Since ventilation is
a primary means of controlling concentrations of pollution generated indoors, this is expected to
have a potentially profound affect on all categories of health impacts associated with exposure to
indoor pollution.
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Outdoor air ventilation was significantly reduced during the energy crisis of the 1970's.
Complaints of building sickness brought about the recognition that indoor air pollution can be a
major public health threat and that adequate ventilation is important for acceptable indoor air
quality.
Implications
A major effort to install more energy-efficient ventilation equipment and more effective and
efficient ventilation strategies may be needed. These changes would reduce the energy used for
ventilation and mitigate the need to save energy by reducing ventilation rates. Such strategies
could include more reliance on natural ventilation or greater ventilation efficiency (e.g.,
displacement ventilation).
Efforts to increase control of indoor pollution sources and promote the use of advanced filtration
and air-cleaning technologies could allow ventilation rates to be modestly reduced without
affecting indoor air quality.
Elevated Ozone
Elevated levels of outdoor ozone due to climate change are expected to increase ozone levels
indoors where people spend most of their time, and where the public is traditionally advised to go
when outdoor ozone levels are high.
Ozone indoors is known to react with a host of commonly used chemicals and produce toxic
byproducts to which people indoors are exposed. The byproducts include fine and ultrafine
particles, formaldehyde and other aldehydes, acrolein, and other chemicals. Other byproducts are
unstable compounds that stimulate additional chemical reactions.
While elevated ozone is rapidly emerging as an important indoor air concern, the specific health
impacts are not well understood. Nevertheless, it is thought that the often-cited health impacts
from ozone and particulate pollution outdoors may in fact reflect exposures to toxic compounds
indoors from ozone reaction byproducts.
With ozone levels expected to increase, this issue may be one of the most important indoor
environmental impacts on public health due to climate change. Important chemicals of concern
indoors because they react readily with ozone include terpenes, which are natural oils
increasingly used in fragranced products and cleansers (including many "green" cleaning
products). The rapid growth of fragranced products and air fresheners may be of particular
concern in view of climate change. This issue is worth further study.
Implications
Fortunately, it may be possible to mitigate the potentially significant public health impacts from
direct exposure to ozone and from exposure to byproducts of chemical reactions with ozone
indoors.
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Strategies to reduce direct exposure to ozone indoors could include the use of air cleaning
systems to remove ozone from outdoor ventilation air and from indoor air. Charcoal and other
chemical sorbents are used to remove ozone within filtration systems and are suggested for use in
high ozone areas. That these systems require careful monitoring and diligent maintenance
emphasizes the need for improvements in building maintenance. Further research into improved
gas phase air-cleaning systems may prove to be highly beneficial.
The most direct strategy to reduce exposure to ozone-reaction byproducts is to have
manufacturers change their product formulations to reduce the use of those VOCs that readily
react with ozone. Filters typically found in HVAC systems may also be a cause of concern when
ozone levels are elevated. Filters continually collect dust particles that containing VOCs that may
react with ozone to create undesirable byproducts such as formaldehyde that is then delivered into
the indoor spaces. In fact, formaldehyde has been shown to be a common product of reactive
chemistry on filters (Hyttinen et al., 2006). The synthetic media of the filters themselves also
appear to be a problem (Buchanan et al., 2008). This suggests the possibility that proper filter
medium selection and alternative filter media or treatments could reduce adverse health
symptoms from chemical reactions with ozone.
Extreme Water Events
Extreme water events from heavy rainfall, flooding of interior rivers and streams, and flooding in
coastal areas caused by sea level rise are expected to put great strains on the building stock,
increasing infestations of molds, rodent, cockroach and dust mites.
Allergy, asthma, and respiratory effects from these problems are expected to increase
substantially. Problems are likely to be made worse by power outages and infrastructure damage
caused by extreme weather.
Providing temporary housing for displaced populations is expected to increase in areas
susceptible to flooding. Exposure to formaldehyde in temporary housing has been a problem and
will likely become a far greater problem unless provisions are made for removing formaldehyde-
laden materials from these units. Problems caused by inadequate ventilation and poor drainage
have also been experienced in some of these structures.
Implications
Delays in the ability to pump out water and dry buildings will likely extend exposures well
beyond the events themselves, and these exposures may become endemic if the time needed for
recovery extends beyond the time between extreme water events.
Areas where buildings are perpetually wet or very damp from extreme water events may become
uninhabitable and abandoned, leaving large swaths of economically depressed areas and causing
significant population relocation.
Research to identify vulnerable areas could provide advanced warning and time for the
development of mitigation strategies. Codes, standards, and the widespread dissemination of
guidelines to protect buildings from damage where possible, and to mitigate dampness and mold
problems, may be useful.
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Ecological Shifts
Ecological shifts are expected to alter the breeding cycles and geographic distribution of many
disease vectors, and this trend raises the potential for major disease outbreaks in the United
States. The globalization of commerce and increased international travel adds to this threat. The
increase in UV radiation from climate change also has the potential to compromise a person's
immune system, making the population more vulnerable to disease.
Implications
Reduced ventilation in buildings could expand the potential for disease transmission.
Building O&M practices could be critical elements of control, particularly in hospitals, medical
centers, schools, and other high-occupant-density buildings.
Cultural attitudes in the building community that consider maintenance to be an expense to be
minimized rather than an investment to be made in building environmental quality may need to
be addressed through educational and training programs. A change in attitude and a move toward
more scientifically based maintenance and cleaning practices would be needed.
Policies and guidelines specifically addressing disease transmission may need to be developed,
widely disseminated, and promoted.
The improved design and construction of temporary housing would help protect the health of
displaced occupants housed in these facilities.
Economic Costs
The undiscounted public health costs of climate change impacts on indoor environments appear
to between the high tens of billions and two hundred billion dollars per year. These are annual
costs that would occur toward the end of this century valued in current dollars. Using social
discount rates of 3 percent and 7 percent, the public health costs appear to be in the low-to-mid
tens of billions of dollars per year, and would likely be in the high tens of billions of dollars per
year if the full range of health effects were included in the estimate. These ranges represent the
current value of discounted annual costs that are expected to occur indefinitely into the future.
Implications
From a public policy standpoint, the impact of climate change on indoor environments and public
health appear to be at levels that would warrant more attention. Focused study is needed to
determine how best to ensure that policies, building practices, and technologies are implemented
to prevent the degradation of indoor environments and ensure that buildings can fulfill their
primary role of providing indoor spaces that are supportive of occupant health, comfort, and
productivity in the face of climate change.
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